Hello,
I am having issues with incoming calls on 3CX behind a Sophos XG firewall. Sometimes incoming calls will connect after 10+ seconds and sometimes they won't at all. This previously ran behind a Pfsense firewall without issue, so I know it is related to the XG. When I run the firewall check on 3CX I get “full cone test failed” on the SIP port, tunnel port and media (9000+) ports. Outbound calls work fine. Tech support from Sophos tried several steps to diagnose and fix the issue without luck.
On the Sophos XG I have:
- Disabled the SIP module
- Modified the UDP timeout value to 150
- Have forwarding rules for SIP, Tunnel, Management and Media ports.
- Outbound rule for the 3CX server with Rewrite source address enabled. Use outbound address is SourceNAT which is the same IP address as the incoming rules.
Any ideas what could be causing the issue?
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