Phones won't register after VMHost upgrade on Debian/3cx VM - broke - solved

[princer800]

We updated underlying Vm host from 5.5 to 6.5. Everything went fine and system returned to operation.However about half of the phones would not register- that is show no service. We could re-provision them from Factory default - buttons and other config cleary worked but phones did not register.
This is a system spread across 4 sites with a central 3CX Debian VM. Webclient worked, if phone was registered things worked,and so on.
Very weird in that Provisioning worked fine - but couldn't register. But no way to tie it to a location or type of phone,etc
A Fortigate Firewall is used to route the various VLANS at the central site.
Traffic across those interfaces is wide open and obviously no change at that time.
After several hours the problem turned out to be "Sessions" on the firewall that were persisting.
They were linked to the UDP traffic sourced from 3CX server on port 5060.
Once those sessions were cleared (ultimately reboot of FW) the problem went away.
So not sure why this happened but something to keep in mind if similar symptoms exist.
The fact that some phones worked and others didn't was particularly weird!
Upgrade of VMWare at best required shutdown/restart of 3CX. Very likely that MAC address of 3CX server changed. But again didn't make much sense.

 

[cobaltit]

So I can't seem to locate the VMware guide but I know the Hyper-V guide says you should use a static MAC address. You would want to do the same for your VMware instance.

 

[princer800]

So I can't seem to locate the VMware guide but I know the Hyper-V guide says you should use a static MAC address. You would want to do the same for your VMware instance.

Yes, would agree with that being the same on VMWare.
Seems to me the only thing that would make sense of "what changed".
Hopefully this might help someone else if similar things happens.