Weird upload speed issue BPI-R4

Banana Pi Router design BPI-R4(MT7988)
1

I use BPI-R4 as my main router. ISP 1Gbps cable is plugged in WAN port.

Also I have my PC and a wifi router (Gl Inet MT-6000 Flint 2) connected to LAN ports.

When I use speedtest.net to test my network speed from my PC, I have 500 Mbps Download /500 Mbps Upload speed, as it should be. When I use it from any wifi device on my network (iPhone, mac, dell laptop) there may be 2 cases:

  1. 500/500 Mbps and it’s ok
  2. 500/10 Mbps and it’s not ok. If I test my speed on PC and then on wifi again, it becomes 500/500 again for some time and then it goes back to 500/10.

When I use Keenetic Giga instead of BPI-R4, there’s no bug and everything works ok.

Is this known issue? Any workaround?

If not, how to troubleshoot it?

2

This is most likely an RF noise issue, which has been discussed here. TL;DR: take a look at the SNR figures for wireless clients, find a better Wi-Fi channel, change the way the pigtails are routed inside the case, populate SFP cages. None of those is a complete fix, though.

3

I don’t use BPI as a wifi router so there are no pigtales inside the case, no SFP. Just BPI-R4 router.