Solved Recurrent Intermittent FQDN public IP address changing

[ArchieLucy]

Hi and Thanks
Hope this is correct forum for IP address, FQDN problems.
History:
Problem with the FQDN public IP address intermittently recurrently changing for over 6 months. Voice calls go through OK, even with unwanted public IP bound to FQDN. I only discover the problem when I want to log on via the http://XXXX.3cx.us. Login to web portal is is only for occasional remote management, so I don't really know how often the IP/FQDN is changing. Today I wanted to login again, found the problem active again decided to ask for help. If I login again in a few days the problem will most likely be resolved. Or I can force resolution by changing from Static Public IP to Dynamic Public IP for few minutes, then changing back to Static. Waiting an hour or so, and the correct IP will be bound to FQDN.
At no time do I change the static IP address on the pbx or in the firewall.
The incorrect IP address is from an unused Comcast account which is still active. Unused means the Comcast modem is turned off, and disconnected from the LAN at the site of the pbx.
Pbx is local install.
The incorrect Comcast IP address was in use untill 9 months ago when we changed to ATT (new static public IP addressed)
The onsite firewall was searched for any entry of the old unwanted IP address. None found. Firewall firmware upgraded.
The local pbx has gone through several upgrades since the problem started.
It's a windows 10 pro installation of 3cx.

Version Number of pbx

16.0.619

How can this problem be resolved such that the correct static public IP is always bound to the FQDN?
How do I trouble-shoot this?

 

[leejor]

The IP will normally correctly identify the IP that the PBX currently resides behind. So I have to assume that for some reason (Comcast IP is data-filled somewhere?), it is still linked to that IP.. Did you ever have another instance of 3CX, running behind the Comcast IP, that may still be active?

 

[ArchieLucy]

Excellent, yes. Debian 3cx, guest vmware os
However the instance was turned off in 2020, I keep it as an emergency backup.
I checked the instance before answering your post. It does have the offending static IP from the Comcast Account.
Even though it is always powered off, I powered it own, changed the offending static IP to the correct static IP. Powered the instance off again.
Who knows maybe somehow a powered off debian instance caused the issue?
IF the offending IP address doesn't return, I'll call that a solution.

 

[ChrisC_3CX]

Just to clarify, if you're using a 3CX FQDN and the IP is changing to one that is not correct, it means that, without a doubt, there is a 3CX PBX contacting our activation servers with that wrong IP address.

Excellent, yes. Debian 3cx, guest vmware os
However the instance was turned off in 2020, I keep it as an emergency backup.

If this instance was configured with the IP you used to see when the issue occurred, then this is most probably the one causing the issue. If you've changed the IP to the correct one in the 3CX Management Console then it should be enough to sort this out. If the issue persists then it is either a different 3CX instance causing the issue. This provided of course that the main one is configured ok and is not itself causing the issue.

I do also have to mention that you should never have two or more instances running with the same License Key unless you are utilizing a 3CX Failover configuration. I know you said one of the two is always powered off but still, just having it there will potentially cause issues in the future that may affect activation or FQDN resolution such as in this case, etc.

 

[ArchieLucy]

Wow, thank you for such rapid and informative reply.
Today I'll delete the second instance that is powered off, since fresh installs from backups are so each, doesn't make sense to keep it anyway.
In few weeks if the FQDN with incorrect IP continues we should know if somehow the incorrect IP was coming from the old (supposedly inactive) debian instance. Does that make sense?

 

[ArchieLucy]

Thank you so for guidance.
I found another out of date active install of the 3cx on the same LAN with the unwanted IP address and same FQDN. Uninstalled it.

 

[ChrisC_3CX]

Thank you so for guidance.
I found another out of date active install of the 3cx on the same LAN with the unwanted IP address and same FQDN. Uninstalled it.

Nice job on finding the culprit, that was definitely it!

Glad we could assist, don't hesitate to start a new thread should you need anything else!