Linksys Router Issue

[Trinithis]

A while ago, I got a Linksys BEFSR41 v4.2 router to hook 2 computers to a DSL internet connection. The router connection type is PPPoE (a manual suggests to have it this for DSL). It works fine and dandy except when I enable port forwarding for any application, in which case, every minute or so, the internet connection disconnects and reconnects some 20 seconds later. If I disable the forwarding, then the problem is solved. However, I need the ports opened for some of the applications I want running.

Can anyone help me with this problem? (FYI, I don't know much about what I'm doing.)

[tech_support]

Have you tried resetting your router?

[Twey]

The other stock response is to update your firmware.

[lainlives]

I get the same problem, if your adapters in your pc's came there or are cheap/old then it is them, we get this problem with one pc here.

[ItsMeOnly]

OR, your ISP has DSLAM that detects different packet metrics (suggesting more computers connected to the line), and kills your connection. Is using a router allowed in TOS of your ISP? Also, the "applications" might be blacklisted in TOS as well.