GL-AX1800 Flint with Sonoff DW2 Wifi

Routers
3

I have some sonoff as well, try one of these:
1 - Enable IGMP Snooping - IGMP Snooping - GL.iNet Router Docs 4
2 - Disable WMM
3 - Try to switch sonoff firmware to tasmota - https://tasmota.github.io/