How could it possibly be my router causing connection issues?

Readers of game enthusiast forums have undoubtedly seen the sometimes heated exchanges between the It's all gotta be the GAME, crap developers! crowd, and the It could be a problem on your end gang.

I'm of the latter, if you've read any of my posts.

I produced a guide based on helping users in BFBC2 and other games, called Troubleshooting Multi-Player PC Game Connectivity Issues that covers many of the often subtle conditions that can cause connectivity issues for online games. This is rather long - there are many interacting factors that can cause these problems. Some may not have the time to read it, some just won't, sticking to their guns of It's all gotta be the GAME!

I've been attacked by a few, questioned by many. That's fine (the latter, at least), skepticism is good. Ignorance isn't!

I've compiled a list of references for those that want to take the time to see what experts in the field, and real users of many other games, have to say on this matter. In particular, there are much more detailed NAT technical information and the issues involved covered in some of these. It was not practical for me to include this level of detail in my document - it would have become a hardbound book!

If you're really interested in answering the question How could it possibly be my router causing connection problems? , these will help you get there. It will also help you to understand how things can be fine in every other game yet broken for a certain few games, with different users having differing experiences.

I've also included links to forum posts for many games, and many platforms, clearly showing that this kind of issue happens all the time.

Perhaps with a clearer understanding, these may help you solve your own connection problems.

They should also help you to dispel the myth of 'port forwarding has to be used' often repeated in forums. A read of Port Forwarding: Slaying the Mythical Dragon of Online PC Gaming will clarify how NAT and port forwarding are related, and why forwarding ports blindly is unneeded and potentially problematic when used.

Good reading!

References for NAT technologies and issues involved:

Superb overview by Geoff Huston of CISCO
http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_7-3/anatomy.html

Nice overview by the author of RakNet, with success/failure charts:
http://www.jenkinssoftware.com/raknet/manual/nattypedetection.html
http://www.jenkinssoftware.com/raknet/manual/natpunchthrough.html

IETF recommendations for NAT behavior:
http://www.ietf.org/rfc/rfc4787.txt

A very good overview, with diagrams:
http://en.wikipedia.org/wiki/Network_address_translation

For the absolute bibles for NAT and other TCP/IP technical information:
http://preview.tinyurl.com/yefzpfv
http://www.amazon.com/TCP-Guide-Comprehensive-Illustrated-Protocols/dp/159327047X

AnalogX NAT and Nat traversal issues overview:
Interesting test of 100 consumer routers. DGL-4300 top rates, Apple /3com/US Robotics the worst.
Only 43% of routers properly supported full cone NAT.
http://www.analogx.com/contents/articles/nattraversal.htm

A game developer talks about problems with NAT of differing types by consumers:
"If it is a router, it's the user's problem to solve it."
http://forum.unity3d.com/viewtopic.php?p=233448

Other forums for games where users have the same issues some have with game "X".
These same users could well be playing game "Y" without issue.

http://forums.gamesforwindows.com/p/1860/23980.aspx
http://utforums.epicgames.com/showthread.php?t=665969
http://support.microsoft.com/kb/840420 (Microsoft? What would they know?)
http://utforums.epicgames.com/showthread.php?t=602500
http://forums.epicgames.com/showthread.php?t=616452
http://www.dslreports.com/forum/r19418084-Gaming-Mode-Why-does-Dlink-recommend-disabling
http://www.dslreports.com/forum/r20554921-Xtreme-NAT-help-with-Netopia-2241n006
http://support.microsoft.com/kb/941207 (More Microsoft. Maybe they know something about networking?)
http://www.gtaforums.com/index.php?showtopic=353023
http://forum.instantaction.com/smf/index.php?topic=3631.0
http://blogs.msdn.com/johnmil/archive/2006/10/29/nat-traversal.aspx
http://www.gtagaming.com/forums/archive/index.php/t-103945.html
http://www.xfire.com/nat_types/ (widely used Xfire, and problems NAT can cause in the wrong router)
http://forums.electronicarts.co.uk/fifa-10-sony-playstation-3-microsoft-xbox-360/840675-game-no-longer-available-still-9.html
http://www.ureadit.com/solutions/home-network/79-xbox-live-compatible-router.html
http://www.gtagaming.com/forums/archive/index.php/t-103841.html
http://forums.eu.atari.com/archive/index.php/t-59626.html
http://www.bing.com/search?q=full-cone+nat+games&first=51&FORM=PORE
http://forums.eu.atari.com/archive/index.php/t-62799.html
http://openarena.ws/board/index.php?topic=3261.0
http://www.poweredbygamespy.com/services/view/category/connect/ (Gamespy - they brag at only having 10% failure of NAT)
http://boardreader.com/thread/Port_Restricted_Cone_Nat_Router_l9xyXvexg.html
http://text.broadbandreports.com/forum/r22505721-HSI-Known-NAT-problem-with-Charter-HSI
http://computerhelpforum.org/forum/networking/f43/full_cone_nat/t18037.html
http://forums.gametrailers.com/thread/nat-type-1-question/1042731
http://forums.epicgames.com/showthread.php?t=665969
http://www.bgforums.com/forums/viewtopic.php?f=58&t=12277

There are a myriad more, Google is your friend!