Why is not WLAN Router recognized?

I have already asked the question, but I wanted to update it.

My laptop as well as my Kindle find both my WLAN network no more. What can this be?

Smartphone and Ipad think so.

Vielleicht times the router from the power… PC shut down. Wait… Turn on the power on the router again PC boot up. And then it would have to go again. There are sometimes network conflicts that occur.

Maybe the visibility switched off (SSID).

Restart everything. Router, laptop and kindle.