Thanks for the answer. OK, I started figuring it out on my own and I found out that only 2023 port works fine with my SamyGO but I need to use pure telnet client from Windows instead of PuTTY. Any other port does not work.
Anyway, I was able to put some commands, I got results and I ran oscam from the console. I did it only for test purposes but it seems to be working very nicely:)
BTW, full telnet for me means that I can freely input shell commands and I receive normal answers from the console. While using putty, I was able only to input a command but did not receive anything from the console. But I resolved it through a different client.
Best regards and many thanks to the authors of this superb project

The only thing I observed was that it took around 1 minute to start up the whole SamyGO widget after turning on the telly. I think that it would be great to implement oscam autostart script somewhere earlier so that it runs just after turning the tv on.