I'm having the same exact issues as McGoo777 and others.

My Limewire was working fine for the past 2 years plus (through several upgrades) until last week. I didn't do/add/change anything. I had just renewed my membership a month earlier. Had no problems. Then couldn't connect. So I upgraded again to the new 4.18.3. Still can't connect.
I've gone through every step in the help section and on this forum. still no go.
Yesterday, when I booted up, I was SUDDENLY able to connect. Hadn't done anything differently.
Now today, I'm back to no connectivity. This needs to be fixed. or I will cancel and demand a refund.