Symptoms: Unable to connect with or even see servers.
Cause: Certain antiviruses will block Freelancer from establishing a connection.
Solution(s): For the most part, such issues are hard to fix. Unless the antivirus has a clear interface through which the user can unlock specific programs (in which case it likely doubles as a firewall, see point above), there are but two things to do: wait for an update (compatibility is often broken and restored with patches, as was the case for AVG) or change your antivirus. Either way, be sure to look through your antivirus' documentation for information on possible port blocking or program exceptions available.