G7Eleven

We constantly get the question of why DSCP and TOS tagging does not work after following the 3CX blog on this very subject

There are some important pieces of information missing from that blogpost.   The first most important piece of information is that this method will only work if the PC is domain joined.    Microsoft have in their wisdom not enabled this feature for standalone PC configurations.

The next obvious problem with the 3CX post is that the method they mention would tag ALL packets leaving that machine with priority.   Obviously this is not good if the machine is downloading updates, or generating other traffic out via your router.

Follow the process on the blogpost from 3CX, but at the point when you add the rule, make sure to specify the following applications: (you need to add three QoS rules).

3CXMediaServer.exe
3CXPhoneSystem.exe
3CXTunnel.exe

Which will look like this in your Group policy editor after you have added all three rules:

Once you have added the rules, the packets leaving your network should be immediately tagged so that you can go ahead and configure your router to prioritise the traffic.