Game Version

• To access the server list, "Team Fortress 2" must be updated to the current version. Although the Steam client usually patches games automatically, it can miss updates, particularly if the game has not been run for a long period of time. Also, patches can be missed if the game is not set to update automatically. Access the "Properties" panel and check the "Update" tab for this information.
  
  

Ports

• Servers not appearing in the list may be caused by not having the correct ports open on the router. Consult the router manual for the exact steps needed, as this can vary from model to model. The following ports must be open: UDP 27000 to 27015, UDP 27015 to 27030, TCP 27014 to 27050 and UDP 4380.
  
  

Firewalls and Virus Protection Software

• Firewalls and virus protection software must have exceptions added for them to allow game traffic. The process is different depending on the specific piece of software used. Information can be found in the "Help" menu, with the documentation provided with the software or on the manufacturer's website on how to complete this procedure.
  
  

Drivers and Other Updates

• The drivers for the network adapter should be periodically checked to ensure that they are up-to-date and functioning correctly. Operating system patches, particuarly network and security patches, should be downloaded and installed if they are out-of-date. Finally, the Steam client itself must be kept up to date to properly see all of the available servers.