Could you point a way to check if a port is released at Win 10 firewall?

1 see what firewall profile (domain/public/private) is active
2 activate logging of dropped packets in that profile
3 look at the log and you know.

For tcp sessions one can use the tooling that is intended to be used on that port.
f.e.  for 443 one can try to access a webserver, for  port 22 one can try SSH. etc. etc.

alternatively one can use the telnet command to make a connection telnet targetip targetport.
(assuming the server process is running on the win10 system.)

Sorry.
A litle hard to follow your instructions.
Could you give me an easy steps directions?

After enabled telnet at my PC


That means:   Could not open host connection on port 7890. Connection failed.

So it's not available.

I'm going to open another question to get instructions on how to correctly opens this port...

That does not tell if the firewall is blocking it. Possibly yes, but you would first need to know if it's even listening and 2ndly, if any router in between might have rules to block it (hardware firewall).
So better simply use the firewall log as I suggested.

After enabling firewall logs at Win 10 and repeated the previous command:
(I don't know if I correctly catched what you meaning)


The log file is empty...

The firewall log is updated once per minute, so it could be just a delay.
You could provoke firewall population by blocking a port and then trying to access it (like block 445 and then try to access a share from remote).

If still nothing shows up in the log, you configured the wrong profile.

Well
After all the 7890 port opened.
A service had to be started as console mode before must to open this port, something I had no success before.
Another configurations problems arised with no relation with firewall.

Thank you for guidance and suggestions!