Your phone can't connect to the Wi-fi network XYZ How can I fix this?

[Windows Central Question]

"Your phone can't connect to the Wi-fi network XYZ"

Lumia 640 phone connects fine to my home (Actiontec) router.

It doesn't connect to my girlfriend's (TrendNet) router.

The home router is newer but both routers support WPA2

I've tried with SSID broadcast enabled and disabled on the TrendNet router.

I've tried changing the channel.

I've tried moving the nearby portable phone to another room.

I've tried "reset your phone".

I've tried pressing volume and power controls at the same time.

I get the same "your phone can't connect" message whether or not I enter a legitimate passphrase or a fake one.

 

[Guytronic]

Re: "Your phone can't connect to the Wi-fi network XYZ"

Reset the router that the phone won't connect to.