Solved FQDN Issue? Registration Failed: Destination Is Not Reachable

[technomojo]

I've just completed a fresh install of 16.0.619 (Pro Annual) on Windows 10 Pro, v2004, completely up-to-date.

I believe the firewall and port forwarding is configured correctly; the firewall check completes successfully.

This is the full error I receive when attempting to register:

Registration at [SIP Provider] has failed. Destination (sip:XXX.XXX.XXX.XXX:5060;transport=TCP;lr) is not reachable, DNS error resolving FQDN, or service is not available.

I've spoken with the SIP provider, their service is online and we ran a test using PhonerLite. There doesn't seem to be any issue at their end.

When I ping the FQDN externally, it gives the correct IP address (which I've confirmed is still correct), however there are no actual pings. "Request timed out" x 4.

I took the semi-functional 3CX installation offline about 24hrs ago, formatted the Windows PC and reinstalled about 10hrs ago (not a restore from backup). Could this have caused propagation issues at the 3CX end, perhaps?

If it helps, the SIP provider is Internode (AU), who are not a certified provider but were 3CX-friendly before certification was a thing. End users don't want to switch

Internode had been working mostly OK until this reinstall. Just the odd dual-registration after Internet interruptions or blackouts.

All suggestions welcome!

 

[Saqqara]

On the 3CX PC, can you ping the SIP provider DNS record ? If so does it resolve to the correct IP address

If it does not, then you have an internal network issues, that is stopping the 3CX machine resolving names.

What are your dns settings on the 3CX server ? Have you tried changing them to google 8.8.8.8 and 8.8.4.4.

Does the 3CX server have full internet access, nothing is blocking access ie. firewall

 

[technomojo]

Thanks again for your reply.

Yes, 3CX PC pings the SIP provider's DNS record no problems. Incidentally, I've also tested registering using their IP address instead with no luck.

Current DNS settings on the 3CX PC are:

Preferred: [local gateway]
Alternative: 8.8.8.8

I'd prefer not to change this unless absolutely necessary since I'm working on the machine remotely

Yes, the 3CX PC has full internet access; just the Windows firewall.

 

[Saqqara]

What happens if you do a tracert to the dns or ip address, can you see the traffic going from the building.

Compare the responses from another location - the end servers should be the same.

 

[technomojo]

Yes, they seem to complete as expected from both locations, ending with the SIP address.

 

[Saqqara]

I see it is trying a TCP connection, what are you settings under advanced for the sip

Check your transport protocol - it may need UDP or change it to any

 

[technomojo]

That was it!

I changed it to 'Any' and it registered straight away.

Much appreciated. Thanks again!