Christopher Bolin sent along the following helpful tips for setting up Quake II on a LAN:

These instructions assume your server machine is also the machine you use to access the Internet (and have TCP/IP bound to a dialup adapter)

  1. Open the properties for Net Neighborhood. If TCP/IP is already there and bound to your net card, skip step 2
  2. At the properties for Net Neighborhood. Click the Add... button and select Protocol. under Microsoft, choose TCP/IP and then hit OK. This should add TCP/IP and bind it to your net card.
  3. In the list of installed network components, select the TCP/IP bound to your net card. Select Properties.
  4. Make up a fictional IP address. (since 192.168.x.y addresses are not valid on the Internet, it is a good idea to use these -from Voodoo Extreme) I chose 192.168.66.1 for my server machine.
  5. For Subnet Mask, type in 255.255.255.0
  6. WINS Configuration should be disabled, as should Gateway, DNS Configuration, Advanced, Netbios.
  7. Click OK on the TCP/IP properties and you should be back at Network properties. Make sure that on the Identification Tab you have a workgroup specified and on the Access Control tab Share-level access control is enabled.
  8. For the rest of your machines (assuming they are clients), repeat steps 1-5. For step 4, be sure you use a different number for the last in the dotted notation address for each of the machines. For example, I chose 192.168.66.2, 192.168.66.3, 192.168.66.4 etc.
  9. For all the client machines (I didn't find it necessary to do this on the server), under TCP/IP properties, Enable WINS Resolution and for your Primary WINS Server, specify the dotted notation address for your server. In my case, this was 192.168.66.1.
  10. Restart your machine and Quake2 net support should work fine, and your dial-up account should remain intact working exactly as it did before!

I can't promise this will work for everyone, but it should. I'm also not entirely sure that specifying the WINS server for your clients is necessary.