Desktop Screen/Mic Sharing - Meeting on LAN

On a 1 gibibit LAN, what is the simplest way I can watch a Windows 10 computer's screen and have a conversation with the user while watching their screen? Here are some requirements: 1) The solution needs to work without an internet connection on a LAN. 2) The solution needs to offer decent performance (at least 10 frames per second) 3) The solution needs to work without a 3rd party server (computer to computer) Internet services like Jitsi and Google Meet are too demanding for the ADSL internet connection that the LAN uses. Plus, I see no point in streaming video out of the network in order for it to come right back in (to another computer in the same network). It would be awesome if jitsu could function as desktop application that could locate and list meetings on the LAN.