You need to set up a TURN server in combination with a WS server (for signaling) or use a third party service like Agora. TURN and WS are very easy to setup even on a VPS. I have been working in this field for 5 yrs now. I can walk you through the entire process. It will require a lot of trial and error (both the fronts viz Server and code) but it's doable. Recordings can be saved on device as well as on the server.