same here - “splitting” the 2.4 and 5 into WLAN and WWAN did the trick and solved the instability for me.

btw - the OP mentioned originally using the RAV Power WD03 in a stable way and then becoming unstable when flashed it with OpenWRT. this is exactly my own experience and it is why I bought the AR750S-Ext, although I am quite happy with my 750.