AC750 EX3110 won't connect to device

I just bought this AC750 | EX3110 WiFi Range Extender but it won't connect to any devices.

My iPhone, MacBook pro and my girlfriend's Samsung Galaxy S9 don't connect.

 

The extender is plugged into a horizontal outlet less than a foot away from a Claro Technicolor wifi router. (I'm in Puerto Rico)

 

My devices all recognize the extender, showing me my routers name with the "_2GEXT" and "_5GEXT" suffix.  The extender doesn't recognize the password for the router tho.  It kinda things about it, the little green "Device" light coming in for a breif second then turns off.  My device telling that its the wrong password. 

 

I've reset it, powered it down, reset it and reset it to the point of insanity and can't find anything helpful on the forums for my problem.

 

Am I missing something?  

 

Please help.

 

Thanks!