1st Time GL-X750, can't connect to my Wifi network

Put Power into the GL-X750
waited , found it in my wifi List on the smartfone
connected, logged in, switched language
Now i try to connect to my Fritz!Box , tried in 5ghz tried in 2.5ghz, but nothing happened

and 2 little Bugs/Glitches, Preview Eye not viewable and Beitreten should be Verbinden

Tried it with the PC to connect over Wifi, no Problem.
Now i went to my smartphone, connected it to and my Wifi Router is displayed.

Mmmh, ok , now it works.