Choose any port between that range. They are all free from being used by any official net program. Port 64049 is a popular one to use.

I presume your router is set to UPnP. In that case you cannot change it, however listening port changing is important. This in itself might fix the problem.

Before we suggest other things, try these suggestions first: If LW Will Not Connect (click on the blue link)

If problems still with connecting, you could port forward your Actiontec router for the computer with connection problems.
Step 1 which is the most important one: Static ip for Vista

2. Router instructions - look for your model Actiontec. Choose a high number port as I suggested here, not the default port 6346.