Firewall/NAT

I'll have my m0n0wall running happily for days on end....and after a while, it'll stop opening new connections (i think this may be partialyl due to my ISP on their side....however)

the problem is, m0n0wall's firewall state's diagnostics page tells me I have like...30 connections open, and I'll be the only person using my internet, and just have firefox open or something.....nothing that would constitute having 30 ports open.

so my question is.....how do I get monowall to close those connections if they've become idle for a time?  maybe I could have it set to reset the state every day or do?

thanks