Zephyr Squad app shows error as "504 Gateway Time-out"

that was not the resolution to our issue unfortunately.  not sure what changed, but the proxy was blocking traffic 

Reboot, and in the browser can you connect to https://manage.smartbear.com:443 if not it would seem that traffic is blocked to this address.

Finally got it working by switching default browser from internet explorer to microsoft edge

Having the same issue