I've been having serious TP issues the past 2 weeks or so. I tried EVERYTHING shown on the Firestorm and LL support pages. The problem is absolutely somewhere between my cable router and LL; even turning off the router firewall didn't work. I filed a very detailed ticket with LL that is still open and perhaps they'll find something. (If so, I'll report back here.)
BUT as a shot in the dark, I turned on my VPN (I use HideMyAss) and set it to a location in Dallas, TX. The problem has disappeared. If I turn the VPN off, the problem returns.
So I offer this for the good of the order. Using a VPN is something I might suspect as a cause of a problem; so you might not consider trying it as a solution!