I have tried the things you suggest i.e.

DISCONNECT/RECONNECT LW
CHANGE LISTEN ON PORT
DELETE LIMEWIRE'S PREFERENCES FOLDER
DISABLE ULTRAPEER CAPABILITIES, DHT & TLS
Checked I have the latest JAVA
I uninstalled and reinstalled LW.
I have 'allowed' LimeWire in my system firewall.
I checked my router, though I have no idea what I'm checking for there. There are no entries at all in the firewall there.