BPI R64 144 Mb/s max, cannot reach 800 Mb/s

Hello, I cannot get my R64 to run at the advertised 800 Mb/s Wi-Fi speeds (no extra modules installed, don’t have MTK7615), and it seems to use only 1 band (144 Mb/s) and the reach is really bad, almost no signal in next room with 4 3dB antennas. Could it be driver issue, or antenna issue? I am completely lost and new to openwrt and Bpi routers.

Running OpenWrt 24.10.0, same issue on 23.05.5. Tried images provided by Bpi from around 2021, which are extremely unstable and still seem to max out at 144 Mb/s link speed.

Thanks for any help

Do you try wifi to r64 or to a client connected via ethernet

iperf ethernet speed is 940 Mb/s, so that is probably not the issue. Issue is only with Wi-Fi. Ethernet works perfectly fine

Any ideas? Could a 5dB antenna help or is it simply an R64 issue