You may have encountered such weird things put in your modem with two bandwidths, 2 if don’t time, patience or. 4GHz and 5GHz see but not 5ghz, try methods this post. Your computer only sees the one of 4GHz after that, problem should resolve can connect to internet again. This might be caused by driver issues be.
Before you move on, it’s suggested that update first If don’t time, patience or