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.


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


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.

10 Gigabit Ethernet on Raspberry Pi 5

Raspberry Pi 5 comes with PCI Express connection and a number of HATs (hardware attached on top) and Bottoms (the opposite of that) are now available for sale. That unlocks some very exciting options. Let’s see how fast can a 10 Gigabit Ethernet adapter on Raspberry Pi 5 go, shall we?

Pineberry’s HatDrive! Bottom proved to be really handy for converting Pi’s PCIe connection to M.2 M-key format. My Kalea-Informatique 10 Gigabit adapter uses exactly that, so that’s a match. Why did I choose this adapter? Very unscientifically this time – it was the first readily available and I was in a fail-fast mood :)

10 GbE adapter connected to Raspberry Pi 5
Pineberry HatDrive! Bottom board with 10 GbE network adapter
Detail of the AQC107 chip powering the network adapter

Enable PCIe port on Raspberry Pi 5

First things first. We need to enable the PCIe connector on the Pi.

sudo nano /boot/firmware/config.txt

# Enable the port

# Configure PCIe Gen
Enable PCIe and configure mode

Build custom Linux kernel and include the Aquantia driver module

Vanilla Raspberry Pi OS doesn’t include the Aquantia AQC107 kernel module. So we need to burn a micro SD card with a vanilla Raspberry Pi OS Bookworm image, boot the Pi 5 and build a customised kernel.

git clone --depth=1 --branch rpi-6.8.y https://github.com/raspberrypi/linux
cd linux/
sudo apt install flex bison aptitude -y
sudo aptitude install libssl-dev
make bcm2712_defconfig

Edit the config file:

sudo nano .config

Add these 2 lines to .config file:


Trigger customised kernel build on the Pi. This will take some time, so bear with us, please.

sudo make -j4 Image.gz modules dtbs
sudo make modules_install
sudo cp -v arch/arm64/boot/dts/broadcom/*.dtb /boot/firmware/
sudo cp -v arch/arm64/boot/dts/overlays/*.dtb* /boot/firmware/overlays/
sudo cp -v arch/arm64/boot/dts/overlays/README /boot/firmware/overlays/
sudo cp -v arch/arm64/boot/Image.gz /boot/firmware/$KERNEL.img
uname -a
sudo reboot

After reboot, the LED light on the network adapter should come to life and we can capture first impressions.

Adapter recognised
10 Gbps Full Duplex
lspci -v output


First thing you will likely notice is how hot this network adapter runs. It runs at 85° Celsius in idle which is slightly worrying and you can literally burn your fingers if you are not careful. Thumbs down on the thermal design front.

High idle temperature

Under load, surprisingly, it ‘only’ runs 0.5° warmer.

High temperature under load

How fast can it go then?

Raspberry Pi 5 officially supports PCIe Gen 1 and Gen 2. It is not certified for Gen 3.

PCIe Gen 1 mode

In this slowest mode, I got 1.71 Gbps/1.53 Gbps iperf3 TCP results with standard iperf3 settings. No jumbo frames, no other tweaks.

PCIe Gen 1 throughput

PCIe Gen 2 mode

Again, with standard iperf3 settings, I measured 3.44 Gbps/3.04 Gbps TCP throughput between 2 computers both connected to 10 Gbps switch ports via 10 GbE Full Duplex.

PCIe Gen 2 throughput

In idle conditions, this setup draws 7.5 W, and 8.9 W under 10GbE adapter iperf3 -R load (3.45 Gbps). Using more iperf3 parallel streams (the -P parameter) did not help at all.

Power draw

PCIe Gen 3 mode

The adapter supports PCIe Gen 3, but it doesn’t work with the Pi. The Pi is not certified for Gen 3, so I can’t say anything bad about this. The Ethernet adapter is not recognised in Gen 3 mode, and no interface is present in ip a. Sometimes the Pi will fail to boot.

According to dmesg, the Pi forced Gen 2 mode:

brcm-pcie 1000110000.pcie: link down
brcm-pcie 1000120000.pcie: Forcing gen 2
Forcing PCIe Gen 2 mode athough Gen 3 has been configured

I powered my Pi from M2 MacBook USB-C port. So I thought, I might be running into under-voltage issues. I tested the official Raspberry Pi 27 W (5 V * 5 A) AC power and it made no difference.

Did you upgrade Raspberry Pi 5 firmware?

Yes, I did. It is running the latest version available as of March 2024.

Latest firmware installed

Low CPU utilisation

One feature I really enjoyed is the extremely low CPU utilisation under load. I saw slower 2.5 GbE adapters hammer CPU with interrupts, but that’s not the case for this NIC. AQC107 does really good job at keeping the CPU cool.

Low Raspberry Pi 5 CPU load under network load

Cable analytics

Marvell supports Cable Diagnostics feature which uses TDR to measure cable length and detect Ethernet cable for defects. Unfortunately, it doesn’t seem to be supported on the AQC107 chip.

Cable Diagnostics not supported

Can you get 10 Gbps out of this adapter at all?

I am glad you asked. How does an Intel NUC with this 10 GbE adapter sound? I’ve just tested it, here you go.

Intel NUC with 10 GbE adapter


The high operating temperature really makes this adapter something I can’t recommend. With maximum throughput below 3.5 Gbps, I think you would be better off choosing a 2.5 Gigabit Ethernet adapter, which runs cool and delivers 2.35 Gbps/2.35 Gbps throughput.

Have you tested any other 10 GbE adapter? Did you get better results? Did you find any 2.5 Gbps Ethernet adapter that supports Cable Diagnostics? I am all ears.

Special thanks

Thanks to Luke Jenkins for exploring and sharing the kernel build instructions. Also, thanks to the WLAN Pi team. You can buy the team a coffee using this link.

Wi-Fi 7 comes to WLAN Pi M4

With the WLAN Pi team, we have designed and launched a M.2 adapter from A-key to E-key, which allows you to install a certified Wi-Fi 7 adapter Intel BE200 to your current WLAN Pi M4.


Is WLAN Pi selling ‘keys’ now? 😉

What is a ‘key’? It is formed of the notch on the Wi-Fi adapter PCB, and plastic blob separating pins inside the M.2 slot. The idea is to prevent users from plugging incompatible cards to the slot, and avoid any ‘magic smoke events’. Here is more about M.2 and the individual key types if you are interested.

WLAN Pi upgrade kit

Since Intel adapters use E-key and WLAN Pi M4 uses A-key, we needed to build an adapter. Badger Wi-Fi has the upgrade kit in stock. It comprises of the Oscium M.2 A-key to E-key adapter, Intel BE200 Wi-Fi 7 adapter, and 2 little bolts to secure the adapter and the Wi-Fi module.

Here is how the ‘butterfly’ setup looks like. Intel BE200 sits onboard of the A-key to E-key adapter, installed in the M.2 slot.

We are ready to connect existing tri-band antennas, and assemble the unit.

Software support

Make sure to either upgrade Linux packages to their latest versions using sudo apt update && sudo apt upgrade command, or download and flash the latest WLAN Pi software image on your SD card. Release 3.2.0 supports Wi-Fi 7 Intel BE200 adapter out of the box with no effort whatsoever on your part.

Wi-Fi 7 in action

For this demonstration I use a consumer Wi-Fi 7 router TP-Link Deco BE85 BE19000. Simply because it is available, Wi-Fi 7 certified, and it supports 320 MHz channel width – not that one would deploy that in an enterprise environment, but mainly to test the maximum Wi-Fi throughput of the Pi.

A bug in macOS doesn’t allow Macs to correctly recognise Wi-Fi 7 networks. Instead of Wi-Fi 7 320 MHz wide network, my MacBook reports Wi-Fi 6 and 160 MHz wide channel. So, we will use another WLAN Pi and its Wi-Fi radio as a Remote Sensor in WiFi Explorer Pro – you need the Pro version to do this.

Nice, Wi-Fi 7 AP!

Wi-Fi 7 network

Connecting the WLAN Pi as a Wi-Fi 7 client only takes few lines of wpa_supplicant config.

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
Wi-Fi 7 network settings

And we have successfully connected the WLAN Pi as a Wi-Fi 7 client to the AP using this command.

sudo wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf -i wlan0
WLAN Pi connected as a Wi-Fi 7 client

Run this command to make sure the WLAN Pi requests an IP address from DHCP server running on the router:

sudo dhclient -i wlan0 -v

What channel are we using? 320 MHz channel width? Indeed.

Adapter and channel details

Before you ask, distance between the Pi and the router is sub 1 meter. What is the Wi-Fi data rate? We are using Wi-Fi 7 (EHT), 2 spatial streams, MCS 12 and 4096-QAM and short guard interval of 0.8 µs.

Data rates

We can refer to Francois Verges’ MCS index tool to check how we are doing. Yes, I have tried, but I have only been able to achieve MCS 13 extremely rarely.

MCS table

How far from the AP can we maintain 4096-QAM?

I hardly ever achieved MCS 13. To maintain MCS 12, I had to stay within about 1.5 meter distance from the router. I got best results with antennas position in this ‘V’ pattern.

My noise floor was -96 dBm and RSSI typically between -29 and -39 dBm.

V-shaped antenna placement

With a different client device designed for Wi-Fi 7 from the ground up (with professional quality antennas and placement), I would hope for slightly longer MCS 12 and MCS 13 range.

It’s throughput test time

It’s time to run an iperf3 test and see how much traffic we can actually push over the air and also how much the WLAN Pi M4 can handle. Here is our test setup. I recommend the OWC 10 GbE Thunderbolt adapter (it uses Thunderbolt protocol, not USB) connected via USB-C to your Mac.

With the help of Oscium WiPry Clarity 6 GHz spectrum analyser connected to another WLAN Pi, we can monitor the life spectrum and see how much red the iperf3 test introduces. We are able to achieve download TCP speed of 2.27 Gbps and upload speed of 1.74 Gbps.

I used iperf3 -c -P32 -R to test download speed, and iperf3 -c -P32 for upload. Number of parallel streams set to 32 provided the best performance.


Wi-Fi 7 works well on the WLAN Pi M4. In fact, it works better than Wi-Fi 7 on Windows 11. We have covered Intel BE200 on Windows 11 in this blog posts.

I was expecting 2.5 Gbps-ish throughput, which we have got quite close to. During the test, CPU of the WLAN Pi was running around 80 % utilisation, and interrupts were reaching 100 %. So, hardware of the WLAN Pi itself posed a bottleneck.

mpstat 1 300 -P ALL
High CPU utilisation due to interrupts

Orientation of the antennas mattered more than I expected to. Best position was a ‘V’ shape with antennas positioned away from the board. With AUX antenna placed 90 degrees relative to the Main antenna, data rates and throughput dropped. Perhaps there is RF noise from the board itself coming into play.

Use SSH key stored on GitHub instead of an SSH password to access your WLAN Pi

By default WLAN Pi, and Linux in general, uses a username and password-based SSH authentication. It involves quite some typing, some brain capacity to remember the password, and it is not the most secure method either.

You can create a public and private key pair. Your SSH client automatically logs in using the private key. The SSH server uses the public key to confirm that you possess the right private key. No password needed, and it also is more secure. The private key is never sent over the network, and this method protects you against man-in-the-middle attacks.

The beauty of this GitHub method is that GitHub stores your SSH public key centrally, which you can easily update, and you can install it to the machine you want to SSH to, by a single command ssh-import-id-gh. You can even add this to a startup script so that it automatically updates your trusted keys.

Let’s do this

ssh-keygen is the program that generates a public/private key pair on your local system. The private key is stored in ~/.ssh/id_rsa, and the public key is stored in ~/.ssh/id_rsa.pub.

The security of this method depends on keeping the private key safe and secure. Make sure not to leave the private key behind.

ssh-keygen -t rsa -C "your@email.com"
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/jiri/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /Users/jiri/.ssh/id_rsa
Your public key has been saved in /Users/jiri/.ssh/id_rsa.pub
The key fingerprint is:
The key's randomart image is:
+---[RSA 3072]----+

Display the public key, which is a text file at the end of the day, and copy its content to clipboard:

cat ~/.ssh/id_rsa.pub

Save this public key to your GitHub account. Browse to github.com, log in, and open Settings:

Click New SSH key, name the key, paste your public key from the clipboard and save it:

To verify that your key has been added you can browse to https://api.github.com/users/jiribrejcha/keys, where jiribrejcha is your GitHub username:

The last step is to SSH into your WLAN Pi or Linux machine and tell it to use this public key from my GitHub, where jiribrejcha is my GitHub username:

ssh-import-id-gh jiribrejcha

If the command isn’t installed, you can fix that by:

sudo apt install ssh-import-id

Passwordless SSH access

When you authenticate to a server using public key authentication, the SSH client offers a copy of the public key to the server and the server then compares it against the keys listed in your ~/.ssh/authorized_keys file. This key was added automatically by the ssh-import-id-gh command. If the key matches, the server indicates that it is able to proceed with the authentication. The private key is then used to sign a message that includes data specific to the SSH session. The server can then use its copy of the public key to verify the signature.

We have just SSH’d to the Pi without a password prompt.

Special thanks

To Colin Vallance for sharing this tip.