Mid ride and suddenly the Zwift app stops and drops me out. Wifi is fine as playing music etc but it seems to disconnect.
This is using it on wifi on a MacBook using the MacBook screen for display and so no other factors.
So the app completely exits and drops you back to the desktop? If so you can send the game log to support@zwift.com and get some advice. They may send you to this support document which tells you to install macOS updates and if that doesn’t help then send in your logs. Issues With Zwift Crashing
WiFi problems rarely cause game crashes, though music/video streaming is not a good indicator of uninterrupted WiFi since those services have buffering in order to avoid interruptions.