I'm always observing an audio delay at least about 300ms. Whenever I make a call, there is a delay. Also when communicating via internal only (LAN no routers or QoS) as also on the echo test *777 Thought it was related to the Hyper-V environment and/or Linux release of 3CX. So I have installed 3CX on a standalone Windows 10, and the problem is the same. I have tried to change connection settings on the yealink T46S phone, as also connecting other phones. The delay is also present on android client. Currently I'm using 15.5.3554.1, have tried to update to 15.5.3849.1 the delay was the same. But afterward the firewall check was never ending, and I have to hard reset the VM. So I was reverting to 15.5.3554.1.