Resolve network connection issues on a Windows 10 PC in LAN

I have a small LAN and one of the PCs (Windows 10) started to behave weird after a Windows update. Here it how it behaves: - This PC can be seen on the network. If I ping it from other computers, it works. - The shared folders on this PC can be accessed by other computers correctly. - But programs on this PC that must respond to requests made by programs installed on other devices with access this PC in either ethernet or wifi by [IP:Port#] , now don't work anymore. These programs used to work properly before and I think the change in behavior happened after a Windows update. An example of such program is "Winpopup LAN Messenger" ( [login to view URL] ) I checked the network advanced sharing settings and it's set like before (Turn on network discovery, Turn on file and printer sharing). I disabled the firewall / windows defender. With netstat -an command in cmd prompt I can see that those programs are listening to the UDP ports that they are supposed to listen to, however they don't respond to incoming requests from other machines. I can give Teamviewer if needed. Please bid only if you know how to troubleshoot the issue. Automatic bids will be dismissed. Thanks.