5. The Last Mile - Common PC Problems

Troubleshooting PC problems comes with the territory of hosting a LAN party. The following tips should help you locate problems more quickly.

Does the machine have an Ethernet card?
Once you've stopped laughing, send them up to the hardware vendor to buy one. Someone actually once said to me "You said wireless access would be available", thinking that wireless meant he didn't need a network card!

Is the Ethernet cable connected?
If not, connect it and make sure you check the Link and Activity lights before walking away.

Connected, but no link light?
First use a known, working test cable and see if that works. If that solves the problem, sell / give them a new cable, or have them see if they can borrow one from a buddy. I also suggest you get the player's permission and then cut off one of the ends of the bad cable so they know not to try using it again. (Usually it gets thrown back in a box just to cause another network admin trouble later if you don't.)

Still no link?
Try a different port on the switch, again with the known good test cable. If this works, you probably have a bad port on your switch. Switch back to the original cable, but in a new port and they're on their way. Make a note of the port and switch number of the bad port and put a piece of tape over the bad port to prevent others from encountering the same problem.

Still no go?
At this point you're looking beyond the simple stuff. Possible causes are corrupted drivers, network stacks or other software-related causes. It's also possible that the NIC is just dead. The last possibility is chip-level compatibility between the NIC and switch that causes speed and mode (full / half duplex) autonegotiation to fail. You might be able to fix this if the NIC driver (or utility) allows you to set speed and mode. Otherwise the user is probably looking at having to get a different NIC.

Client DHCP Issues

Check with the appropriate utility for your operating system to determine whether a PC has a proper IP address. (ipconfig on Windows, System Preferences on Mac OS X, ifconfig for 'nix and BSD distros)

Make sure the IP address doesn't start with 169, which is Windows' automatic local private addressing that it defaults to when DHCP fails. If you see a 169.X.X.X IP, try releasing and renewing the IP address of a known good system to make sure the problem isn't with your DHCP server. I suggest you first try this from another table that has not reported prior problems, then from another PC at the problem table.

Firewalls

Firewalls can sometimes also cause problems with DHCP. They usually do not block DHCP traffic itself, but have been known to cause other problems that interfere with obtaining a proper PC lease. You can try shutting off the firewall, but you'll be more certain to remove any firewall effects by uninstalling it entirely - with the user's permission, of course.

Gamers reporting trouble seeing game servers on the network should first check the version of their game to make sure it's the latest version. If that checks out ok, then 90% of the time a misconfigured or too-securely configured firewall is probably blocking server response packets from returning to the game's server query broadcast.

Test the game without the firewall enabled, tweak the firewall as necessary, or just run without it. If you shut off the firewall, I suggest you disable File & Printer Sharing on the NIC as a precaution if the user doesn't need it. This will prevent problems from nasties that spread via this mechanism.

WINSOCK and other TCP/IP stack problems

Spyware - I hate it. It kills PCs. It also kills Winsocks. If a person is getting an IP address fine, but nothing much else seems to work, it's probably because the Winsock has been compromised by spyware. To resolve these problems, keep a USB key or CD-ROM handy with Spybot Search & Destroy and Ad-Aware SE. Be sure to update each of these with the latest definitions from the same key or CD if possible, or an Internet connection if available.

If after running both of these spyware removal apps, you're still having problems, there are a few more things you can try. A System File Check (SFC) can be run on an XP machine by Start > Run and then entering "sfc /scannow" (note the space before the /scannow) into the Run box and putting an XP CD into the drive when prompted. You can also try reinstalling the Winsock per the directions in MS KB299357.

If you have a Linux machine that can't see game servers on the network, it's probably because there isn't a default gateway assigned to the NIC card. This one eluded us for an event or two until we were able to do some testing ourselves. Neither Windows nor Mac OS exhibited this behavior.

Assigning a nonexistent gateway on your network is detrimental to its performance, so if there's no Internet connection at your LAN Party, then you can advise Linux users to manually add a gateway to their systems and this problem will go away. If they are unsure how to add a default gateway, they can do so from a shell prompt by executing the "route add" command like this: