Turn it off
Turn off the firewall on the router.
You don't really need it anyway behind a NAT.
Get rid of UPnP unless you need it.
I would though want to know what was creating so many connections. Sysinternals (now microsoft owned who seem to have managed not to spoil it) tcpview is nice. If no process is listed for the offensive traffic you might be able to get a clue from the target address.
No installation necessary, download and run :-)
Sometimes a sloppy programmer will not bother to close the connections. The router handle this with a timeout. You may be able to reduce the timeout.
Last edited by jimjim1; 21st Nov 2014 at 13:04.
Reason: added UPnP bit