I always had problems from the beginning, with Android and with CoreELEC, with the 5 GHz WiFi connections on my H96 Pro+, this TV Box was freezing randomly (it could be after a few minutes, after a few hours or after several days). As the 2.4 Ghz connections are very slow and do not support HDTV well, I finally put a 2.4/5 GHz USB WiFi adapter with antenna. It works very well.
First of all I installed the best firmware I know of Beelink GT1 Ultimate, then I installed CoreELEC in the internal memory, then I reprogrammed my remote control to turn on and off the TV Box, and finally I installed the new WiFi adapter. It’s been like new.
The installation details are here: