Olivier Langlois's blog

I found your blog searching around for a solution to a big problem people are having with Company of Heroes. Namely, connecting to games. It seems that COH uses some complex method for connecting to people, rather than specifying a certain port for all communications. Is there a way to tell COH which port to use for communication? Would this help connectivity anyway?

Also, me and my roomate both have valid copies of COH, and have lots of problems trying to connect to the same game, apparently because we are connecting from the same IP address/ connected to the same router.

I found your blog very informational at least for the info on NAT.

I'm not sure what NAT my router uses, I tried to find a utility that would tell me, but was unable to.

I actually have two routers.
Trendnet TEW-452BRP
Netgear MR814v2

I bought the Trendnet one more recently because it offers faster wireless. Currently, the NETGEAR router is connected to the cable modem, and the Trendnet one is connected to the NETGEAR. I don't know if that causes problems.

If you could give me any info on this COH connection problem, it would be much appreciated. Do you work with the relic online team? Maybe you could kick some guys in the shins and get em' to fix it, if they aren't already working hard at it.

Thanks,
Eric

Hi Eric,

COH should always use the same port. Once the game is launched you can verfiy this yourself by typing from a Command Prompt (DOS window):

netstat -a -b -p UDP

In the command output, you should find the COH executable listed and using the port 9103 if my memory is correct. However, even if COH would use an arbitrary port, lets say because port 9103 is already in use by another application, it should not affect COH game operations if the router is setup correctly (no DMZ settings for a specific port in the router).

I am not sure what you mean that your roommate and you are trying to use the game from the same IP. If there is more than 1 computer in your private network they must have different IP addresses. In the network configuration of Windows, You should choose the DHCP option. All routers that I know have a DHCP server that dynamically assign to the connected PCs their IP address.

I do not know the routers that you have listed in your comment but the setup described should be fine except that if your computer has to go through 2 NAT devices, you are augmenting the risks of being affected by NAT issues. Why don't you try to connect directly your new router to the modem?

For the NAT diagnostic tool, I know that Quazal provided one to Relic. If you ask them for it, they might accept to provide it to you. Otherwise, I do not know any other NAT diagnostic tool available on the Internet. The only one I know is if you have a friend that have a Xbox or a Xbox 360. When you browse the console networking settings menu, there is an option that diagnose the type of NAT device that you are using.

Also, most NAT routers do not support well when more than 1 PC are used to play the same online game and the sad thing is that there is no way to tell if a router is going to do the job by looking its spec because router NAT behavior is usually undocumented. The only way to figure out is to experiment. Try to find a router that is RFC 4787 compliant or that have an Xbox Live compatible logo on the box. Then plug it in your setup, test if it works and if not return it back to Best Buy.

Good luck!
Olivier

Another interesting tool is WireShark (http://www.wireshark.org/)

Make sure that you filter in only UDP packets and you should see very interesting things about COH network traffic. Among other things, I believe that you should see the other particpants IP address in clear text when a COH Match start.

This info could help you to figure out why your setup does not work well when you and your roommate try to play simultaneously from the same private network.

Thank you very much for your detailed response. I did try to put the newer router connected directly to the modem, which does seem to work better.

I only meant that my roomate and I are behind the same router (same 'outside' IP).

Still some games I cannot connect to, but more work than before, so it's bearable now.

Once again, thank you.

I got that RelicCOH was using UDP ports 9100 and 6112, which would occasionally change to 9101 or 9102, etc.

-Eric