If you holding the reset button according the procedure for about 10 seconds and nothing happens then maybe the power outage has damaged your device. You should seek a local support assistance.

Obviously that's intermittent, but not persistent. When that happens what's the distance between your phone and the router, are you receiving a good wireless signal from your router on 5 GHz band ?...

Try by forgetting that 2.4 GHz network and re-connect it again.

@Gaia If you can't connect to the router by wireless try to connect your computer by cable to one of the router LAN ports and see if you can access the router's management interface. If you still...

What do you mean by sometimes can see them, sometimes can not ? When you see them how do you try to communicate with them ? What are those devices phones, computers ?

@Imran0321