edit: Actually, looks like I have no network connectivity on the new install. Could you help me with that, still?
In the System info > Network, it says "Link: Not connected". Under LibreELEC > Connections, nothing is shown. Previously, this is where I connected to my Wifi.
Do I need to do something to enable the Wifi on my device, to get my AP to show here?
I need some log from your box. Please log in to the box via SSH over Ethernet, then put this in the command line:
dmesg | paste
... and post the link you received here. Hopefully, something will be revealed about the state of your wifi, because unfortunately I don't know what kind of wifi chip is in your box.