That range of ports are free. Not used for any official purpose. And these are also usually the very last that are blocked by ISP's. Not to say that Plusnet has not decided to block this range after they found you changed ports whilst using LW.

It might be worth calling Plusnet & asking them for a recommended free port to use for p2p purposes, & tell them you're finding some of these free range ones are being blocked & to thus, open them up for you. Speak to a technician there, not someone at the front desk.

The reason ISP's are starting to stop p2p sharing programs is they use a lot of bandwidth & some ISP's are finding they're running out of bandwidth. Their biggest income arrives from businesses so that's who they give priority to.

Something else you can try is connecting at non-peak times. See if it makes any difference connecting during day or evening, etc.