That's usually a good idea.
I think it uses ports 6881-6889 from memory, I may have said this in another thread (as I recall having typed something about BT a while back). This just goes back to Winston's request, when asking for help -- providing necessary details (such as network setup, configuration, OS, etc). I didn't think you were having problems with speed, (your first post indicated that you were uploading more than you were downloading, but you did not make mention of any 'significant' speed reductions, over an extended period of time).
It's good to hear that you're now geting full speeds though. Glad it worked out for you, all the best.