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VOIP over VPN has multiple dropouts per second

Hello,

I run a 3cx on premise that has to be accessed through an OpenVPN tunnel on a Sophos UTM9 firewall. Unfortunately, it is only possible throug VPN because the users work on a terminal server (RDP). In there the 3cx web client runs on a web browser.


After a few tests it turned out that everything is OK without VPN. When the tunnel is on, there are many short dropouts per second. If you concentrate you can barely understand what the other person said.


Do you have any idea what may be the issue?


Here are some more details:


- internet connection with 350 MBit Up / Down (measured)

- Sophos UTM 9 with

      - Bandwidth prioritization each 5000 Kbit/s for PBX / RDP / VOIP

      - OpenVPN

      - deactivated content filter / IPS


It was tested on client side with 2 Fritzbox routers with each 50/10 Mbits Down/UP and 60/12 Mbit Down/Up with the exactly same result.



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  • Hello Martin.

    I would first check "flood protection" in in intrusion prevention as it is still active when you disable the global tab on intrustion prevention.

    You should see some of those errors within the logs.


    Sophos Gold Partner
    4TISO GmbH, Germany
    If a post solves your question click the 'Verify Answer' link.
Reply
  • Hello Martin.

    I would first check "flood protection" in in intrusion prevention as it is still active when you disable the global tab on intrustion prevention.

    You should see some of those errors within the logs.


    Sophos Gold Partner
    4TISO GmbH, Germany
    If a post solves your question click the 'Verify Answer' link.
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