Solved 3CX is now using IPv6 for phones and call queues

[Chris.Rumans]

We are running 3CX 18.0.2.315. Everything was running great until this morning at 2:30 AM. I came in this morning and noticed that non of my SIP trunks were registered. I rebooted the phone server, Windows 11, and my trunks registered. However, all incoming calls are being told that the phone number has been disconnected. I talked to one of our SIP providers and they said that they were receiving a 404 from our 3CX Server. Looking into the logs, it looks like 3CX is trying to communicate to the phones and call queues using a IPv6 number. Not sure why.. I have checked and made sure that the Windows 11 PC is set to use only IPv4. I have rebooted the server and some of the phones. Where is this coming from?

An example from a log taken just prior to upgrading to version 18 of 3CX, showing that it was using IPv4
05/01/2022 13:26:20:612 | 7 | [CM503001]: Call(C:6456): Incoming call from Line:10003<<12222222222 to <sip:[email protected]:5464>

This is an example from today, showing what I believe is an IPv6 number
21/02/2022 09:46:36:555 | 10 | [CM503010]: Call(C:314): Making route(s) from Line:10006<<+12222222222 to <sip:8001@2620:9b::194b:ba53:5060/UDP>
21/02/2022 09:46:36:555 | 10 | [Flow] Call(C:314): Direct SIP call to <sip:8001@[2620:9b::194b:ba53]:5060>
21/02/2022 09:46:36:555 | 10 | Call(C:314): from Line:10006<<+12222222222 to 8001 doesn't match any known extension number.

How can I get 3CX to start using IPv4 again?

 

[Saqqara]

Try this , under Settings -> Network settings - untick 'automatically bind to IPV6 ***'

 

[mcsphones]

And to be honest, I generally disable IPv6 on any on-prem 3CX installations, as is most cases it just plain isn't needed.

 

[Chris.Rumans]

Thanks to everyone. The "Automatically Bind to IPv6..." was not checked, and I usually do disable IPv6 on the servers. I had noticed that on the Dashboard, under IPv6 there was an address, even though I had it disabled on our network adapter. What I found was that we had a third party vendor that had installed another network adapter and they had IPv6 enabled. Once I disabled this on their adapter, 3CX no longer recognized IPv6. I restarted the SIP Server and everything started working again.

 

[cobaltit]

Yep.. This is why 3CX doesn't support VPNs and multiple adapters except in very specific configurations.

 

[ChrisC_3CX]

Glad to hear you got this sorted though I do have to mention that Windows 11 has not been tested with 3CX and is therefore not a supported OS. just keep this in mind so that if you face any issues you cannot explain or get around you could consider migrating to an OS that is supported before delving deep into troubleshooting.

I will be closing this thread so please let us know if anything else comes up!