Kriss Kliegle KA1GJU
Since routers vary significantly, it's difficult to describe in detail each and every one. My router's firewall is on the default setting of Medium for what that's worth. Never had to adjust it.
As to Windows Firewall, this machine operates as a server for "KA1GJU Airspy Discovery #2 and SDR-iq #2" and there is a Windows pop up asking about permission to which I answer Yes, allow incoming traffic. But as a user, I don't think that applies.
Be sure any other Antivirus is off or add SDRC to it's exceptions, I've been bit by this issue before!
Otherwise, start a new thread with the issue involved (with screen shots attached, LOL) as to get Simon's and others attention. You may have to use the Print Screen key, open in Paint, crop out the garbage, then save, and attach.
73 Kriss KA1GJU