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2 days agoWith TCP there are built in listeners on OSs which you can use to test. Also TCP will work before UDP. For whatever reason firewalls and such do weird things with UDP traffic. I always use a cli tool that I can’t remember the name of for testing.
For built in listeners use ncat, but nmap package is not always included. If you are on Windows find some listener Poweshell script, it will be under 10 lines, with Test-Connection. When I was a SysAdmin one repeated problem was UDP traffic was not working. When you tested the TCP port it would work, verifying that the connection is there, but UDP for a variety of reasons is problematic.