et voilà & Ursula would be best to answer this. But, if you're port forwarding then you should do it separately for both TCP & UDP. If not, then that doesn't matter. If port 6346 isn't doing well, then probably a high no. would be best. 40000 plus I think. But you can try these ones: 37404, 1203, 80, 20282, 443, & 40475.

For a list of legal ports see: A Guide To Alternative Port Selection

Also see the following link & follow all the off-shoot links to find hints & extra skills to help: To continue files downlding (click on link)