I lost connection to the Beam 2 via WiFi.

Did a reset the whole Beam already, did new setup, connected to the wifi, but it looses it directly. 

Also took it off from the power many times. 

Still not found in the app. I do see the Beam in my Unifi config. I restarted the Unifi DreamMachine (router) to avoid other problems and to get rid of 

Any suggestions?