I know you said that you've tried everything, but have you seen this Thread by Birdy?? Lots of good fixes.
At least you're not blocked by a Firewall. That really tends to be the Pain in the A$$. Try the fixes in this Thread, and if no help we can try something else maybe.
If LW Will Not Connect 
P.S. You are so fortunate. You Live on a Beautiful Island. I Live in the Desert