3CX audio and firewall issues

[Fabrice SMi]

Hi, I'm posting this because we have a lot of issues with the 3CX Audio part. Indeed we have sound losses during a conversation and/or (sometimes) the caller or the called can't hear each other during a conversation.
We have a firewall E80 from Clavister and you will find below the example of configuration we applied.
https://secure-online.nl/hrf_faq/configure-clavister-netwall-with-3cx-pbx/
The ALG SIP is deactivated on the device, same goes for our ARUBA 2930 switchs. All devices are in the voice vlan.

However the 3CX Firewall Checker gives negative results.


Can you explain to me what does this test ? Where does the IP packets go? Are the tests done on our public IP? How do we interpret this type of result?
During a wireshark measurement I can see my connection to the 3Cx server but no other packets.
Concerning our internet link we have a fiber link with 10 Mo reserved for TOIP.
Concerning our hypervisor here is the configuration:



Our system is on site (on premise) and was installed with the Debian ISO

The devices we use :
Yealink SIP-T42s FW 66.85.0.5
Yealink SIP-T46s FW 66.85.0.5
Yealink SIP-CP920 FW 78.85.0.5
Provider : myopenip.fr, we are on a 30 MB fiber link

Thanks in advance for your help.
Ps: sorry if my english is not perfect.

 

[JohnS_3CX]

Hi Fabrice,

There is a more detailed explanation of what the test does exactly if you click the "How to resolve" link that appears in the test: https://www.3cx.com/docs/firewall-checker/

The fact that the checker sees the ports being remapped to another port, means that there is NAT taking place somewhere in your network (usually the ISP modem or the firewall).

You will have to investigate those 2 further.