Thomson / BT Home Hub users
Please use the following process and custom file to troubleshoot the issue:
Exit from Steam completely
Download these custom files: MasterServers.vdf
- If the files do not download when clicked, please right click this link and select "Save Target As..."
Place it in your \Steam\config\ folder (You will need to overwrite the current file already in place)
Default location: C:\Program Files\Steam\config\
Right click this updated file and select "Properties"
In the General tab, make sure the "Read-only" box is checked and click OK
Re-start Steam and test the issue
If the issue persists, please complete the rest of this article