if these don't help you ill need more info
what type of server, listen server? source dedicated? srcds?
it was working as an idle server but not as a regular one? that is very strange
there are many things that could be preventing your connection...id advise you run through my list of problems and see if anything has changed recently regarding those. And just something weird ive found, sometimes your server will be completely invisible to most people, then randomly someone will be able to connect, if it was an idle server it may have just filled based on those odd people.
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