No connection possible

I use a AX 1800 for while. Haven t been online with it since 12 weeks, now I try to connect again but none of my devices can connect to it. Not with 191.168.8.1 or with the app on my mobile, which used to work just fine. Always say a connection is not possible, switch of the router and restart the Wlan. Tryed it a couple of times wit no success - any hints? Is there a way to do a “factory reset”

Reset: Repair or Reset - GL.iNet Router Docs 4

If this does not help, try debrick: Debrick via Uboot - GL.iNet Router Docs 4