WiFi network question

I successfully set up a WiFi network involving a sending unit attached to my roof, a receiving unit attached to my neighbor's roof and a range extender inside the destination house. All the equipment is TP-Link.

I can successfully log on, send and receive messages and access the web - but the tenants in the house are unable to log on. That makes a total of 6 other phones that cannot log on. Why am I the only one!? (It's usually the other way around :).

I can't think of any reason, except that my phone was made here in Mexico and all the other 6 phones of different brands, were made in Canada. But that shouldn't make any difference...

Thanks - rev

What happens when they try to log on? Do they get a message that the password is incorrect? What error messages, if any do they receive?

Sorry, I forgot to close this one. The problem was a conflicting IP.