What does it mean? The error seems somewhat contradictory seeing as how the server has somehow passed it’s IP to my client. What are the common causes of this error and are there any solutions?
The issue is most likely a firewall.
The server is advertising to Valve the IP address of the server, which works fine because outgoing traffic gets to Valve ok.
The client is asking for games that match some criteria and the master server at Valve responds with this information just fine.
However, the master server tries to query the server at that IP address to provide extended information and when the server fails to respond (firewall blocking unsolicited traffic), the master server tells the client that this server failed to respond to the request.
Check Valve’s website for firewall/port information (27000-27050 for most of it).