I have an issue with adding one XE75 to an existing mesh network of 2 XE75 routers. The new router just doesn't get detected by the DECO app. It did connect once or twice but then it seemed it then wasn't able to save settings. 

my network:

Internet connection on Modem - XE75 as Main Router - XE75 wireless as AP 

Want to connect a 3rd XE75 as new AP to improve mesh wifi coverage.

What I have tried so far.

- DECO app just doesn't pickup the new DECO although its in blinking blue LED mode.

- restarted all starting from internet modem, to main XE75 and secondary XE75.

The new XE75 sends out its own WIFI SSID (Deco_NNN) and I can connect to that with phone, but not with the DECO app.

Any advise?