google hangout microphone is not working with network error and firewall setting issue
At google Community somebody answered like this:
I have found the culprit. I use Spybot Search & Destroy's Anti-Beacon software to block telemetry data that Windows 10 constantly sends to Microsoft. This is why trying multiple Windows 10 machines that I have configured did not alleviate the problem. Somehow one of the IP block entries it adds to the Windows Firewall now conflicts with Google Hangouts. I will report this to the software vendor.
Source: https://support.google.com/hangouts/forum/AAAAfpFnBZ8mdNNg8LNvNg/