Okay, first thing’s first. Borderlands’ multiplayer support is riddled with problems (online at least), so this problem and troubleshooting guide is not certain to work. Nevertheless, it has helped me overcome some problems and get the borderlands multiplayer online (although still with some trouble…) It’s a shame really as in single player mode, borderlands is mediocre at best- but in multiplayer co op it really shines.
First of all, you need to open the following NAT ports on your router:
7777, 28900, 28910
This should help get borderlands online in a lot of cases. Remember if you have multiple computers behind your router, you must open ports that link to each computer’s IP address. This is a pain in the neck, but is one of the most common problems with borderlands- it is essential to making borderlands online multiplayer work. For more information on port forwarding, visit www.portfoward.com. This site includes router specific guides for opening ports. If you ever have any problems with NAT ports, check here first!
Also, turn off your firewalls and if you have a DMZ, try routing it to your computer before starting borderlands multiplayer. This can help solve a lot of problems, but it is dangerous. Do not leave your system in this state once you’re done playing! Disabling your anti virus protection can solve some problems- but remember to turn it back on again afterwards!
Next, try opening a public game of borderlands and inviting your friends into that rather than running a private game. Many people have reported that this works better, but of course the problems is you need to hope that your game doesn’t fill up before your friends arrive!
When hosting a game, selecting your character before you invite people has also been shown to effect the way borderlands copes. I’m not too sure on this one, but many borderlands players on the tubes insist this can solve some of the problems.
Many people have also reported success with borderlands online multiplayer when starting the single player game and inviting people into that (press O to do this).
Finally, try running borderlands through a third party client such as game ranger. Gamespy have never been a very good company for supplying this sort of thing, and borderlands is no exception to their inadequacy. A lot of people who can’t get borderlands working on gamespy have reported no problems with gameranger.
If you have any further fixes for the borderlands online multi player, please post them below.