@George_RTCS you are now in global mode I think, look at the above right corner, switch it to your controller device, then you can see them again

@EAP-245v4_error does this issue happen with wifi only? How about when you use Lan cable? Is it normal? You can try to set the channel of the eap manually so that they cannot switch frequently...

@EAP-245v4_error it might be not the Eap issue, 1 suggestion that tou can check the stabilization of your isp to see if there is any packet loss or not. Try to open cmd and continuous ping test to...

@Jospher it will take quite a long time to boot up again, about 20-30 mins I think? How long have you waited since it finished the upgrade?

@-RB- I used to have the same issue before, my IoT devices could not connect to dual band ssid. When I disabled the 5Ghz band, they are able to connect again without any disruption until now. And the...

@Bromo have you tried to turn off 5Ghz on the ssid of IoT device and try again? Only enable 2.4Ghz band