There are several factors that can contribute to an echo in your AG9 headset.
- The echo may originate from the person who is talking and not necessarily from the person who hears the echo. For example, if you only hear the echo when talking to a specific person and not when talking to others, the problem concerns the headset connection of the person who is echoing, not your headset connection
- An echo may originate from a bad internet connection.
To make sure the issue is with the headset and not one of the factors above, test the headset on a different PS4 console if you are able to do so.