I pulled the wire out of my wifi antenna when I opened the unit. I put it back but it never worked. I just wanted to mention that I plugged in a cheapo USB wifi adapter, chipset Realtek 8191 and it just worked. It comes up as wlan0 in LibreELEC -> CONNECTIONS.
As a side effect I notice that the signal is much stronger on this USB device and it can see more wireless networks. If you have weak signal issues it might be something to consider.