My LAN speed is not anywhere close to what it should be for a Gigabit NIC. My Raspberry PI 4 is about 5 times faster. I’m running Armbian now. But it was the same on Raspberry OS.
How are you testing LAN speed?
If it helps any for comparison, I just ran iperf3 between 2 of my Renegades running RPi OS and I was getting a solid 946Mb/sec which is pretty much full throttle after taking into account overhead.
I’m using a couple different ways. I one is just a simple file copy to a samba share and the other is to the internet using speedtest.net. Both the raspberry and renegade art plugged directly into the router. I realize the file copy may be a factor of the usb hard drive storage. They are both in USB 3 ports. Speed test for the raspberry is around 450 and the renegade around 80.
I ran iperf3 test. The test said the renegade is similar to the Pi 4. I’m not sure why speedtest.net is so different.
There is some issue with the GUI speed test. I installed the CLI version. The results were much better. They were the same as the PI 4.
speedtest.net test your internet speed which has nothing to do with the board.