Wifi Extender EX6100/AC750 192.168.1.250
The very first thing to check when you are installing/setting up this extender is to make sure your ROUTER is configured to allow IP addresses that are in a range that includes 192.168.1.250. This should absolutely be in the installation guide.
Spent an unusual amount of time with tech support and was encouraged to return this seemingly defective unit. The mywifiext.net site was allowing me to enter new account parameters but looped back to the 'create new account' screen after accepting coordinates.
If your ROUTER supports 200 IP addresses change your range to something like 192.168.1.51 - 192.168.1.251 as this will save you at least 2 aspirin bottles, a very long support call and a ride back to Bestbuy.