@JimH you have not asked a question.
Your first reply
"I'm guessing it's somewhere in the security settings (firewall, antivirus, etc.)."
Your second reply
"Antivirus or other "security" software might allow one and not the other.
Windows updates can also do strange things."
Your third reply
"Windows Defender is part of the Win10 installation and there is a firewall. The wiki has a topic on Windows Defender.
If you want to dismiss my questions, I'll let you work it out on your own."
No questions.
Yes I know that Windows defender is part of the Windows installation. I also stated the firewall rules are set the same as far as I can see for both Media Center 22 and Media Center 23. I went on to ask the question how could the firewall or antivirus allow some of the channels to work and others to not work. The PC is talking to the same IP address of the tuner so if the firewall is blocking network access then no channels should work. I am not dismissing anything you stated and have checked Windows Defender.