resolving 'sip-alg-detector.3cx.com' & testing 3CX SIP Server failed, detecting SIP ALG... not reachable

[mohan.vineeth1988]

Hi,

I use SonicWall TZ300 and have opened all ports as described in the user manual of 3cx. Still, I have issues resolving 'sip-alg-detector.3cx.com' & testing 3CX SIP Server failed, detecting SIP ALG... not reachable.
I had opened all the ports, Disabled SIP Transformations, port remap disbaled, Changed UDP timeout but still have the above issue.

I have attached the firewall checker result

 

[ChrisC_3CX]

Based on the screenshot, it seems the issue is that, as you have also mentioned, FQDN ip-alg-detector.3cx.com cannot be resolved by the 3CX Instance.

What OS is 3CX running on? I would recommend connecting to the machine and running the following commands(Linux/SSH or Win/Command Prompt):

nslookup sip-alg-detector.3cx.com
nslookup sip-alg-detector.3cx.com 8.8.8.8

If the first one fails to resolve the FQDN but the second one does, it means you might have to change the DNS server used by the 3CX Instance. The second one is Google's DNS so if it works, you could simply change to that one.

 

[mohan.vineeth1988]

Hi,

Thanks for the reply. I tried in cmd both nslookup sip-alg-detector.3cx.com & nslookup sip-alg-detector.3cx.com 8.8.8.8. both seems to resolve from the 3cx server
I have attached the screenshot.
Using 3cx on Windows 10 Pro

 

[ChrisC_3CX]

I'll PM you shortly regarding this issue.