How to resolve connection issues to freedb or Web Sources?
First of all, make sure that Mp3tag has access to the internet. This can often be checked by using Help > Check for new version.... If you're getting a response there, you can be sure that the internet connection works.
If Mp3tag can't connect to the internet, please ensure that the Firewall on your system allows access for Mp3tag. Some routers also have program- or traffic-specific rules.
If you have still problems with accessing online resources, increase the timeout value at Options > Networking to 10 and try again.