Full 5 Gigabit Ethernet on Raspberry Pi 5 with iocrest Realtek RTL8126 adapter

I’ve tested a number of 10 Gigabit Ethernet adapters on Raspberry Pi 5 based on the AQC107 chip. One adapter that negotiates PCIe Gen 3, achieves 5.5 Gbps speed and overheats. Another one which only works in PCIe Gen 2 mode and peaks at 3.44 Gbps. And even a full-size PCIe card made by TP-Link which negotiates PCIe Gen 2 link speed and doesn’t go beyond 3.44 Gbps either.

The Realtek RTL8126 chip we are testing today is so far the most suitable for Raspberry Pi 5. It is capable of 5 Gigabit Ethernet at full speed. TCP iperf3 throughput peaks at 4.7 Gbps. It doesn’t overheat. And it doesn’t excessively utilise the Raspberry Pi 5 CPU.

This particular one is sold under the iocrest brand. Like the other boards and adapters there is no increst branding on it and it will likely be sold under various brands. The RTL8126 chip is the key component here.

Raspberry Pi 5 with 5 Gigabit Ethernet network adapter

How did we connect it to the Pi? Via PCIe bus. We breakout the Raspberry Pi 5’s PCIe connector via Pineboards (aka Pineberry Pi) board to M.2 M-key slot. And in that slot we install the iocrest 5 Gigabit Ethernet network adapter – that’s the black M.2 module, plus a PCB with RJ-45 connector on a grey ribbon cable.

iocrest 5 GbE adapter connected to Raspberry Pi 5 via PCIe Gen 3 link
Closer look at the adapter

Here is how it looks from PCI device perspective.

Performance

It has no problem negotiating full duplex 5 Gigabit Ethernet and filling the interface with traffic fully.

5 GbE Full duplex

iperf3 with default TCP settings peaks at 4.7 Gbps up and down. More parallel streams don’t improve the result any further. This is in PCIe Gen 3 mode.

Full 5 Gigabit Ethernet throughput in PCIe Gen 3 mode

Just for the record, if we downgrade PCIe bus to Gen 2 link speeds, we are talking 3.43 Gbps down and 3.31 Gbps up iperf3 TCP throughput-wise.

Throughput in downgraded PCIe bus to Gen 2 mode

Thermal footprint

Fully loaded by TCP traffic, I see temperature of 81.2° C (178° F) on the top surface of the RTL8126 chip. Yes, it is on the warmer side, but Raspberry Pi 5 SoC runs quite warm too and it is nowhere near 122° C temperatures I observed on this “hot” 10 Gigabit Ethernet adapter.

Chip temperature, installed in Intel NUC with M.2 slot

By the looks of it, there is no temperature sensor on the PHY so I can’t measure internal temperature.

CPU utilization and temperature of fully loaded adapter with TCP traffic

Linux software support

I happened to have Raspberry Pi OS with 6.8.0-rc7 kernel running on the Raspberry Pi 5. Out of the box, the adapter did not work. iocrest included driver download link pointing to this Chinese website but I am not so sure I want to use that one.

After installing driver from Realtek’s website, the adapter works just fine.

Power draw

This adapter in PCIe Gen 3 mode draws about 1.5 W in idle, and 2.1 W under full iperf3 load.

Switching the adapter to Gen 2 mode doesn’t make any power savings. I measured 0.1 W less in Gen 2 mode.

The whole setup of Raspberry Pi 5 with fan, Pineboards PCIe adapter, and this 5 GbE adapter in PCIe Gen 3 mode draws about 5.1 Watts in total under full iperf3 load.

Does it work on Windows 11?

Yes, it does. I installed one in Intel NUC 12th generation. It runs at full speed full and Gen 3 x1 mode.

Windows 11 driver (as of May 2024) downloaded automatically via Windows Update only allows this adapter to use 2.5 GbE. To unlock 5 GbE we download driver directly from Realtek’s website and we are all set.

Driver from Realtek’s website with full 5 GbE support
5 GbE full duplex with driver from Realtek’s website
Intel NUC with 5 GbE RTL8126 adapter

With the adapter inserted in M.2 M-key slot, we won’t be able pop the NUC bottom lid back on. The adapter is just a bit too tall.

Bottom lid won’t fit with the adapter installed

Throughput also looks good. I might revisit Windows throughput testing tools at some point. But for now, I take 4.74 Gbps down and 4.42 Gbps up speeds. Increasing number of parallel streams did not improve throughput in any way.

Windows 11 throughput test

For the record, Jumbo frames seem to be supported but I had no reason to explore this further this time.

Jumbo frame support on Windows 11

Summary

As I mentioned towards the beginning, 5 Gigabit Ethernet based on Realtek RTL8126 chip seems to strike the perfect balance for Raspberry Pi 5. It delivers 4.7 Gbps up and down, doesn’t consume much power, and doesn’t produce excessive amount of heat.

Long-time test will tell how it actually performs but for now I am happy with what I’ve seen.

From driver perspective, I am wondering if the latest Linux kernel supports this chip natively or if I can enable the right kernel module manually.

How to connect full-size 10 Gigabit Ethernet PCIe adapter TP-Link TX401 to Raspberry Pi 5 and Intel NUC

It is refreshing to be able to test hardware which actually has a product name :) TP-Link TX401 is a 10 Gigabit Ethernet copper PCIe adapter.

TP-Link TX401 PCIe 10 GbE card

How to connect standard PCIe card to Raspberry Pi 5

I am testing on Raspberry Pi 5 and Intel NUC. Both do have an M.2 M-key slot and they won’t take this card natively, will they?

Pineboards (previously known as Pineberry Pi) makes a great PCIe Gen 3 compatible board that breaks out Raspberry Pi 5 PCIe connector to M.2 M-key slot. And from there we can use another adapter – MZHOU M.2 to PCIe 4X Adapter. It allows us to insert a standard size PCIe card into M.2 M-key slot.

Pineberry Pi M.2 M-key adapter -> M.2 to PCIe adapter -> PCIe card
Pineberry Pi M.2 M-key adapter -> M.2 to PCIe adapter -> PCIe card

The Ethernet adapter is correctly recognised. We just need to build a custom Linux kernel with AQC107 kernel module enabled. Steps by steps instructions are here for your reference. They work for all AQC107 based adapters I’ve tested.

It negotiates 10 Gbps Full duplex link with my switch.

But it only works in PCIe Gen 2 mode on Raspberry Pi 5 in this setup. That means that throughput will be significantly limited to 3.44 Gbps download TCP speed and 3.07 Gbps upload. Using more parallel streams did not help in any way. We are limited by the 4 Gbps throughput of PCIe Gen 2.

I was not able to make PCIe Gen 3 work using this setup. Understandably, high-speed buses don’t like the extra connectors and adapters.

Limited throughput due to PCIe Gen 2

Updated: It wasn’t available back then when I tested this, but Pineboards now sells uPCIty Lite HAT for Raspberry Pi 5 which completely removes the need for the intermediate MZHOU adapter.

How to connect standard PCIe card to Intel NUC

The same M.2 M-key to standard PCIe card adapter works with my Intel NUC 12th Generation.

Standard PCIe card in Intel NUC
Standard PCIe card in Intel NUC

Windows 11 automatically downloads the latest AQC107 driver using Windows Update.

Driver is downloading

It negotiates 10 Gbps Full duplex.

10 Gbps link

The TP-Link card successfully negotiates PCIe Gen 3 x4.

PCIe Gen 3 link speed and x4 width

PCIe Gen 3 allows us to achieve TCP throughput of 9.48 Gbps with no effort in the download direction and 9.49 Gbps in the upload. So this card can clearly do 10 Gigabit Ethernet, it just needs PCIe Gen 3 link speed.

Download TCP throughput 9.48 Gbps
Upload speed 9.49 Gbps

No overheating problem

Unlike unbranded Chinese adapters using the same AQC107 chip, this adapter is designed does not overheat. You can read some horror stories about chip temperatures of 122° degree Celsius (252° F) here.

Idle PHY temperature 58.1° C
PCIe Gen 2 full load temperature 63.3° C
TP-Link TX401 in PCIe Gen 3 mode on Windows 11 runs at normal temperature
Closer look at the heatsink

Summary

This adapter achieves nearly 9.5 Gbps of TCP throughput in either direction on Windows if you allow it to use PCIe gen 3 link speed.

Unfortunately, it only negotiated PCIe Gen 2 with Raspberry Pi 5 and Ethernet throughput is limited to about 3.4 Gbps. So for Raspberry Pi, I would recommend a 2.5 GbE adapter which it can fully handle. Alternatively, a 5 GbE adapter. Coming up next. Stay tuned.

It is a good product though with solid cooling. It still produces some heat but that’s a feature of the AQC107 chip. Its advantage is that it keeps the actual system CPU utilisation low even when fully loaded.

The TX401 is a great fit for a desktop machine. If you run a Mac or NUC, I recommend the external 10 Gigabit Ethernet network adapter connected via USB-C using Thunderbolt 3 protocol. No drivers needed.

2.5 Gbps Ethernet on WLAN Pi M4

WLAN Pi is primarily a Wi-Fi tool, but occasionally I need an iperf server that would be able to deliver more than 1 Gbps of TCP throughput. In a controlled lab environment, I normally use PoE powered NanoPi R5S. I know the IP address of the iperf server by heart. Outside of the lab, I could really do with a WLAN Pi, its preinstalled software, display, buttons and everything it does out of the box. So the question is: “Can we add 2.5 GbE to WLAN Pi M4?”

M.2 slot to the rescue

WLAN Pi M4 doesn’t have any USB 3 ports. How do we add 2.5 Gbps Ethernet to it? If you don’t mind losing the Wi-Fi adapter in favour of 2.5 GbE mGig port, we can install this 2.5 Gbps Ethernet adapter in M4’s PCIe M.2 slot. It is based on Realtek RTL8125B chipset. I paid £17 for it including shipping to the UK.

M.2 A+E KEY 2.5G Ethernet RTL8125B PCI Express Network Adapter

It just works*

To my surprise, it just works*. Yes, I hear you, no one likes these asterisks, do you? 😉 Continue reading, it’s not the end of the story.

WLAN Pi M4 with 2.5 Gbps Ethernet
2.5 Gbps full duplex

The underwhelming default driver

Linux (and WLAN Pi image) has a driver for this adapter, but upload speeds, that is from iperf client to WLAN Pi iperf server, are very poor. We are talking 300 Mbps poor.

Poor 300 Mbps upload speed

Install Realtek’s latest driver to fix performance

Downloading, compiling and installing the latest Linux driver from Realtek’s website fixes the performance issue. We get symmetric 2.35 Gbps of TCP throughput with standard packet size.

2.35 Gbps of iperf3 TCP throughput

Installation of this driver isn’t as straightforward as it might look. I ended using vanilla Raspberry Pi OS image instead of the WLAN Pi one. Mainly because it is not easy to get the kernel headers for WLAN Pi image and we need them to be able to compile the new driver.

Summary

Yes, it is possible to achieve 2.35 Gbps symmetric TCP throughput on the WLAN Pi M4 with this adapter. But you should be aware of these facts:

  • This Ethernet adapter doesn’t fit inside WLAN Pi M4 case
  • You will have to give up the M.2 Wi-Fi adapter in favour of mGig Ethernet
  • From software perspective, the Realtek driver that ships in WLAN Pi image doesn’t unlock full performance of this adapter (iperf client pushing traffic to WLAN Pi iperf server). Installing the latest driver isn’t trivial on WLAN Pi.
  • We, WLAN Pi team, currently don’t support this setup. If you have a use case for 2.5 GbE support on the M4, please let us know.

Portable Catalyst 9136 Wi-Fi 6E demo powered by Zyxel 802.3bt power injector

I am building a portable Wi-fi 6E demo in a box solution. What do I use for that?

PoE powered FriendlyElec’s NanoPi R5S runs iperf3 server. Here a quick iperf3 performance review of this little, 2.5 GbE, and mighty Linux box.

My Catalyst 9800-CL controller is hosted on a cloud, so I don’t need any hardware for that. Finally, my Catalyst 9136 Wi-Fi 6E AP is powered by a Catalyst 3560CX 10 Gigabit Ethernet multigigabit switch.

6 GHz 2×2 MIMO setup powered by PoE+

Catalyst 9136 is Cisco’s premium AP with all the bells and whistles including hexa-radio architecture and built-in environmental sensors for smart building use cases. It requires an 802.3bt/UPOE power source to enable 6 GHz radio in full performance 4×4 MIMO mode. The switch I use supports 802.3at/PoE+, which is great, but 6 GHz radio downshifts to 2×2. And that’s where an 802.3bt power injector comes to the rescue.

Zyxel 5G PoE++ Injector

Cisco’s 5 GbE 802.11bt power injector (AIR-PWRINJ7=) is now available, and that’s my go to option for production use.

Since the Cisco injector isn’t widely available yet, I decided to test this Zyxel one. It provides 802.3bt power and allows the AP to run in full power and full 4×4 6 GHz radio mode with no compromise.

Do I like power injectors in production?

Absolutely not! Ideally you should design for 802.3bt/UPOE switches to power all your new APs via PoE.

It allows you to:

  • easily, centrally and remotely monitor how much power the APs use
  • enable/disable power on a port to bounce an AP
  • leverage redundant Platinum-rated power supplies for the AC to DC power conversion
  • manage the solution with ease – just think how difficult it is to manage more than 1 power injector, the number of AC power sockets, and what happens when someone disconnects the injector?
I still use C3650 UPOE mGig switch in my lab. Catalysts 9300 and 9400 the best choice these days.
UPOE and mGig capable C3650 providing full power to the AP

Final look

Carrying a full-size switch is not really an option for me, because small form factor is my main goal. So a power injector works best for me. But if I could I would love to use a compact 802.3bt switch.

Are you wondering if the PoE splitter connected to my iperf3 server (the little black box with 3 Ethernet interfaces) actually negotiated 2.5 Gbps Full duplex with the switch? Yes, it did. But keep in mind that the PoE splitter is technically only rated for 1 GbE. So use as short patch cable as possible and ideally CAT6.

Still few things to tidy up and perhaps I could build this into a nice Pelican case

OWC Thunderbolt 3 to 10 Gbps Ethernet Adapter – The Fastest Multigigabit Adapter For Your Mac

When it comes to the fastest copper Ethernet adapter for your Mac, you have only 2 options:

  • If your other half approves, get yourself an M1 Mac Mini with built-in 10 GbE port. It doesn’t get much better than this.
  • Or you can consider an add-on 10 Gigabit Ethernet Thunderbolt 3 adapter for your current Mac.

We will focus on the latter today.

Thunderbolt 3, not USB

While the USB-C connector might temp you to connect these adapters to a standard USB port, these adapters don’t support USB protocol. They use Thunderbolt 3 and they happen to use the same USB-C connector as USB. That’s the only thing USB and Thunderbolt have in common. Before you order one of these adapters, double-check that your computer supports Thunderbolt 3. That should be most new MacBooks, Mac Minis, Intel NUCs and similar platforms.

Which 10 GbE adapter shall I buy?

I tested two of these Thunderbolt 10 GbE adapters. One made by Sabrent, and the other by OWC. They both look alike, both perform very well, both get quite warm, and both work out of the box on macOS. Yes, no driver installation required on your part on macOS! 🎉

Mainly because of the loose Sabrent cable issue explained below, I recommend the OWC adapter. It comes with great documentation, and even the Thunderbolt cable itself is thicker, feels premium, and most likely delivers better shielding.

OWC Thunderbolt 3 10G Ethernet Adapter OWCTB3ADP10GBE

From throughput perspective, I personally tested it up to 3 Gbps down and 3.3 Gbps up using iperf3 with default settings. The limitation is on my part, I just don’t have another 10 GbE computer I could test against.

I’ve seen reports of:

  • between 7 Gbps and 8.74 Gbps uplink speeds with default iperf3 settings
  • 9.5 Gbps uplink iperf3 speeds with Jumbo frames enabled

When I reviewed 2.5 GbE and 5 GbE adapters, this setup has become my reference I ran all iperf3 tests against.

OWC connected to an M1 MacBook Pro
Thunderbolt side
Ethernet side
Raspberry Pi 4 for scale
10 Gbps Full Duplex
It supports Jumbo frames including a custom MTU setting

VLAN tagging

The OWC adapter also supports VLAN tagging. Here is my Trunk port with Native VLAN 129:

Trunk port configured on the access switch

Let’s tag all traffic with VLAN 130:

Create VLAN interface on macOS

Verify that we are indeed in VLAN 130:

VLAN 130 is being used instead of the Native VLAN 129

If you only want to use VLAN 130 (without touching the Native VLAN 129), you can disable the adapter itself. VLAN 130 virtual interface will stay up and forward traffic.

Disable the Native VLAN 129 and only use VLAN 130 for all traffic

Sabrent Thunderbolt 3 to 10 Gbps Ethernet Adapter TH-S3EA

I won’t go into the detail, but my main challenge with the Sabrent adapter was its loose Thunderbolt cable. The connection between the USB-C socket on the adapter and the USB-C connector on the Thunderbolt cable is very loose and practically pulls out just by the tension of the cable itself. It might have been just my unit, but I can’t recommend it.

Sabrent Thunderbolt 3 to 10Gbps Ethernet Adapter on the left
It almost felt like it needed some hot glue to keep the Thunderbolt cable connected

What about Windows and Linux support?

I tested the Sabrent adapter on Windows 10. It required a Sabrent driver installation and then it worked just fine. I would assume the same for the OWC.

I don’t have a Linux computer with a Thunderbolt port, so I can’t share anything on that front.

Sabrent 5 GbE Multigigabit Ethernet Adapter

Sabrent NT-SS5G is a 5 GbE USB adapter, which allows you to achieve higher throughput than 2.5 GbE adapters, and break the 2.35 Gbps barrier. It works great on Windows. If you are a macOS or Linux user, I recommend you consider other options like this instead.

The adapter itself is larger than 2.5 GbE adapters, it uses AQC111U chip, and ships with short 2 detachable USB-A and USB-C cables. USB-C port on its back connects the adapter to your computer. A metal shell protects it, serves as a heatsink, and also adds to its weight.

Windows 11

Install the driver from Sabrent’s website and you are good to go. In my tests with this Topton M6 Mini PC, I measured 2.93 Gbps down and 3.44 Gbps up with default iperf3 settings.

2.93 Gbps down and 3.44 Gbps up with default iperf3 settings

In adapter options, you can actually configure quite a few things including Jumbo frame support. Note that these are fixed values.

macOS

I can’t recommend this adapter for macOS users. It forces you to disable macOS System Integrity Protection (csrutil), otherwise it won’t work. It might be okay for a proof of concept or lab setup, but I would hesitate from using it in production.

This is how to install the driver if you were interested:

  1. Install the driver using the pkg file provided by Sabrent. It installs a Kernel Extension (kext), which drives this adapter.
  2. Enable the extension by going to System Preferences > Security & Privacy > enable the extension > Reboot.
  3. After reboot, unplug the adapter and plug it back in.
  4. It should work as long as you leave the System Integrity Protection disabled.

From throughput perspective, it saw download speeds of 3.30 Gbps, and upload of 3.45 Gbps. This was with default iperf3 settings, standard 1500-byte MTU and one stream. Great results considering that this adapter’s USB interface maximum theoretical throughput is 5 Gbps.

In my view, you might be better off buying a 2.5 GbE adapter, which can push 2.35 Gbps up and down consistently and with no driver installation needed. I tested one here. Alternatively, a 10GbE Thunderbolt Ethernet adapter is even faster choice, but more costly, and larger form factor. Or, if your other half approves, treat yourself to an M1 Mac Mini with built-in 10 GbE 😉

Linux

I tested this adapter on 64-bit Raspberry Pi OS running on Raspberry Pi 4. Although the default driver distributed in Linux Kernel 5.15 works, it doesn’t even deliver symmetric 1 Gbps.

Sabrent connected to Raspberry Pi 4
Upload speeds well below 1 Gbps
Default aqc111 driver details

Let’s download the latest driver from Sabrent’s website. Unfortunately that doesn’t seem to be able to compile for 64-bit OS. I tried compiling on 32-bit Raspberry OS, to no avail. If you have any ideas, please do let me know.

So, on Linux, a Realtek RTL8156B based 2.5 GbE adapter might be a better choice for you. Here is the one I tested.

Plugable 2.5 Gigabit Ethernet to USB 3.0 Multigigabit Adapter

Plugable makes this inexpensive 2.5 Gigabit Ethernet USBC-E2500 adapter. It is based on Realtek RTL8156B chip. On Windows and macOS it works out of the box. If you want to use it on a Linux machine like WLAN Pi Pro or Raspberry Pi 4, expect some troubles along the way, but good performance when you get there.

The USB-C to USB-A adapter is allows you to use it with a MacBook (USB-C) or Raspberry Pi 4 (USB-A)
The adapter itself has a plastic shell and is very lightweight

Windows 11

When they say “update the driver using Windows Update first”, they mean it. Windows 11 will recognise the adapter and you can start using it, but the default driver distributed with Windows 11 significantly reduces this adapter’s performance.

727 Mbps down and 2.34 Gbps up with default driver

Now, let’s use Windows Update to download the latest driver.

Don’t forget to update the driver using Windows Update

As you can see, download throughput (from iperf3 server to iperf3 client) has dramatically improved.

1.78 Gbps down and 2.35 Gbps up with updated driver

Although the box suggests Jumbo frame support, Windows driver settings don’t give me any option to edit the MTU size. So, I assume Jumbo frames are not supported.

MacOS Monterey

On macOS, this adapter works out of the box with no additional driver installation required. That’s a very nice surprise. And performance is great.

Symmetric 2.35 Gbps throughput on macOS

Auto-negotiation worked just fine. If you want to configure speed or MTU manually, you can, but Jumbo frames are not supported on macOS either.

Jumbo frames are not supported

Linux

Now the bad news. If you are considering to use this adapter on a Linux machine, the default driver cdc_ncm is a trouble as it only supports 2.5 Gbps Half duplex. Setting Full duplex manually using ethtool command doesn’t work either.

Default driver only supports Half duplex

As you might expect, with the default driver and Half duplex, throughput is very poor.

1.22 Gbps down and 704 Mbps up with the default cdc_ncm driver on WLAN Pi Pro

On WLAN Pi Pro and Raspberry Pi 4 running 5.15 Linux Kernel I managed to fix the duplex issue by the steps listed below. But I hit new auto-negotiation issue between the Plugable adapter and Cisco Catalyst WS-C3560CX-8XPD switch. It took the adapter to eventually negotiate 2.5 Gbps Full duplex around 15 minutes of constantly flapping the interface. Forcing speed and duplex on the Plugable adapter by ethtool did not work. Certainly not ideal, and definitely worth testing before you commit to the Plugable adapter. With other multigigabit adapters, the Plugable had no negotiation issues.

1.7 Gbps down and 2.09 Gbps up with r8156 driver on WLAN Pi Pro
1.91 Gbps down and 2.06 Gbps up on Raspberry Pi 4 using the correct r8156 driver
Raspberry Pi 4 also known as WLAN Pi Community Edition

How to force Linux to use the right driver

To enable Full duplex capability, we need to tell Linux to use Realtek r8156 driver instead of the default cdc-ncm.

  1. Download the latest driver from Realtek’s website
  2. Unzip it and copy the 50-usb-realtek-net.rules file to your Linux machine
  3. On the Linux machine copy this file here sudo cp 50-usb-realtek-net.rules /etc/udev/rules.d/
  4. Reboot by sudo reboot
  5. Verify that the adapter negotiated 2.5 Gbps Full duplex and is using the Realtek r8156 driver.

Portable and affordable 2.5 Gigabit Ethernet iperf3 Server – FriendlyElec NanoPi R5S

What problem am I trying to solve?

Wi-Fi standards have developed and also WAN links are fast and reasonably priced these days. When it comes to throughput testing tools like iperf3 servers, 1 Gigabit Ethernet has become a bottleneck. A Wi-Fi 6E client can now easily generate more than 1 Gbps of traffic, but how do we measure it?

To overcome that issue, I am looking for a reasonably priced portable single-board computer, which can push more than 1 Gbps of traffic. It should be powered via USB-C, battery, or PoE powered, and should be portable to fit in my “just in case I need it” tool bag.

FriendlyElec NanoPi R5S

This little FriendlyElec NanoPi R5S single-board computer (SBC) delivers everything I mentioned above. Let’s have a look.

Dimensions and case

It comes with a well designed aluminium case, which also serves as a heatsink. The whole unit is smaller than the smallest iPhone, slightly thicker obviously. It runs silent. There is no built-in fan whatsoever.

Portable? Tick! By the way, did you know that the original WLAN Pi uses NanoPi NEO2?
Left to right: WLAN Pi, R5S, Intel-based SBC I am also testing, WLAN Pi Pro

Ports

USB-C power input, two 2.5 GbE, one 1 GbE, HDMI useful troubleshooting or demos, two USB-A 3.0 ports

It has two 2.5 Gigabit Ethernet interfaces (LAN1 and LAN2) and one 1 Gigabit Ethernet interface (WAN). Either of the LAN ports delivers 2.3 Gbps of actual useful iperf3 throughput with default 1500-byte MTU and single stream. I used MacBook with OWC 10 Gigabit Ethernet Thunderbolt 3 Adapter and Cisco WS-C3560CX-8XPD switch.

From client’s perspective that’s 2.27 Gbps down and 2.35 Gbps up

Power

The R5S only draws 4 Watts in idle, and can be powered by any USB-C 5V power source. Your MacBook USB-C charger, iPad/iPhone charger, or USB-C battery pack would do. Alternatively, use a 1 Gigabit Ethernet 5V PoE splitter and PoE power the unit. In my lab with a 2 meter cable, the 1 Gigabit Ethernet PoE splitter actually allowed the R5S auto negotiate stable 2.5 Gbps connection with the switch.

PoE powered

Software

FriedlyElec built and published two operating system SD card images for the R5S – Ubuntu and FriendlyWRT. I tested both, and for my use case FriendlyWRT works best. It has a network-centric and easy to use web UI, has iperf3 preinstalled, and delivers great performance.

Initial setup and tips

R5S ships without any micro SD card, so make sure you have one ready to use. Flash the software image to it using Balena Etcher or similar tool.

Connect the WAN port to a network with existing DHCP server. If you are in the same subnet, simply ping FriendlyWrt.local to get the IP address of the R5S.

Then access the web UI or SSH to the unit, SSH is enabled by default. Change the root password now.

Now, this is important! To achieve maximum throughput, delete the pre-configured bridge interface br0, and configure both multigigabit eth1 (LAN1 port) and eth2 (LAN2 port) as standalone unbridged interfaces. Also, tweak IP address settings to your liking while you are there.

eth1 configured as a standalone interface. Bridge interface removed.

Make iperf3 automatically start by going to System > Startup > Local Startup and add iperf3 -s and hit the Save button.

Change CPU Governor setting to Performance. And CPU Minimum Frequency to the maximum value.

Here is the FriendlyElec documentation and introduction to their FriendlyWRT distribution.

Final verdict

This little single-board computer absolutely deserves its space in my tool bag. For the 2 GB RAM model with case I paid $88 including shipping to the UK. Add a Micro SD card and that’s all you need to get started.

Finally, it you need top performance, don’t care that much about small form factor, and money is no object, the latest Apple M1 Mac Mini can be configured with built-in 10 GbE.