It might help if you answer the other questions so we might be able to find the problem & possible solution. Also which isp do you go thru? (I'm not being nosy just trying to trace the problem area!)

Your test is a good result that says a lot.

Sometimes one small trick does it. But sometimes the isp is either blocking or filtering p2p use. Sometimes it's a network/modem/router issue. Sometimes ...

Even a particular version of LW maybe doesn't perform particularly well on one particular system whereas a later or earlier version will ...