I have a similar problem.
I’ve been using a mango V2 and a Chromecast for a couple of years to watch Netflix or resolve weak signals in various hotels around the world. However today it would not connect to the hotel even though my windows PC android phone and the chromecast will.

It sort of connects and says success but then disconnects. The only obvious issue i can see is the hotel SSID has a space in it. “viengkhong 3” . I note there was a bug in SSID with special characters. I’ve upgraded to latest firmware but it made no difference.
Does special character include spaces?