This is a utility that is supposed to phone home and check for firmware updates. Whether I launch it from my USB VNA P9371A soft front panel or from it's location in C:\Program Files\Keysight\Network Analyzer\Service it still fails. Is this expected behavior?
That seems like the server for firmware updates might be temporarily down.
I'm working from home, so I can't try that from my PNA.
But you can download the firmware file you need from the network analyzer support site.
Keysight PNA Series: Firmware, Upgrades, and Support