The only trick is to restart the wifi router.
After 1 or 2 weeks, my companion app is on wifi but won’t get in the “ingame” mode so I have to restart router and it does sort the issue for me.
Only time I’ve seen this is when I’ve been on 2 different SSIDs on the same network (one on Guest for reasons, one on “main” WiFi). I think your turning it off and on again is probably a good idea though!