What HW version is your router?
What FW version is currently loaded?
I would look into getting a external network switch to put between the router and PCs. This will remove the router from processing PC traffic thats it does't need to be processing and keep peer to peer traffic going only between the PC when needed.
What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?
Ensure DNS IP addresses are being filled in under Setup/Internet/Manual?
Turn off QoS options.
Turn off Advanced DNS Services if you have this option Setup/Internet/Manual.
Turn on DNS Relay under Setup/Networking.
Setup DHCP reserved IP addresses for all devices on the router.
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP.
Always keep the FW thats loaded on less you are experiencing connection issues after you have troubleshot the problems. v1.14 is a good version and works well, you can update to v1.15 as well. If you upgrade to v1.2x, you can go back to older versions of 1.1x.
Well I actually had GameFuel disabled altogether, however I tried enabling it and turned off Dynamic Fragmentation, but no luck.
I am on Firmware 1.14, 2008/10/16
I never upgraded from this when I bought the router because the newest firmware at the time was irreversible and everyone said it caused a ton of issues.
Both of the PCs used in these tests are connected via ethernet cables to the router (one is using cat6, one cat5). This has been happening with all p2p games. Even with friends that live close by, I will get terrible connections to them, however they will have no trouble connecting to other people (the same people I get high latency to).