If your network is using a Sophos UTM v9 firewall, ensure you have the correct settings.

You might notice that when using the Sophos UTM v9 firewall, your video traffic experiences problematic levels of packet loss. This is because the default settings on the Sophos UTM v9 firewall include a limit on packet size. The firewall is attempting to prevent DoS and DDoS attacks by limiting certain traffic. By default, this includes the number of UDP packets.

To raise the limits on packet size, go to Network protection > Intrusion prevention > Anti-DOS flooding and alter the settings. The example below shows a Sophos UTM firewall with increased packet rates.

Alternatively, it may be necessary to disable UDP Flood Protection entirely to improve the quality of calls.