These steps contain some self help options plus options to get us remote access so we can connect to the router and see what is going on. There is little we can do remotely by just 'guessing' what is going on, so establishing a remote connection is always the first step to take, if all self help options fail.
Connect to the router via a LAN port, login, and click on the hotspots tab. We need to receive the IP address of the maintenance connection, something like 10.20.x.y or 10.40.x.y or 10.60.x.y.
If there is nothing shown, please reboot the router by powering them down, and up again, then repeat the above procedure.
If neither attempt shows to an IP address (which would enable us to get access remotely and see what is going on), you have three options:
1) Recover the router yourself using this procedure; or
2) Recover the router yourself using this procedure if it is a TP-Link model and the first one fails; or