Audio lagging behind is often caused by latency in your network (or your patient's network connection). Stop and restart the connection and let the audio catch back up. Ensure you and your patient have a good network connection. You need at least 750 kb/s upload and download speeds. You can also make sure no other programs are running in the background of the computer/phones/tablets. Having multiple programs running can slow the connection.
Try Call Optimization if you still experience lagging.