VOIP phone registration error solved

[typoman]

I have a softphone app on my smartphone that connects to a cloud based PBX.  The PBX is a common Broadsoft platform.  If I open the app at home, behind my OPSense firewall, I get errors that it cannot register to the PBX.  If I turn off wifi or get on any other wifi network, it registers fine.  I've been hunting the solution off and on for weeks.  I was looking in the wrong direction since I assumed it had to do with some network topology nonsense on my end.  The solution turned out to be super simple.  I found it in the very last sentence of this article.

"If you are using a Dynamic DNS address, make sure you go to System: Settings: Administration and put that dynamic DNS address in the “Alternate Hostnames” field."

That's all I did.  I added my DynDNS hostname to that field and it was fixed.