I have an application that is receiving connections from the internet on port 4443. It was working 100% but stopped all of a sudden. The port forward is correct on my FritzBox 7390 router and my firewall is disabled as well as Bitdefender. I have no AV installed. When I format my pc it works and after some updates it blocks the port again. I tried to add the rule on the windows firewall to allow the port but no luck.