This happens at least half a dozen times over the week.
Setup: Roon core running on Windows 10, client running on ipad Pro with ios 13.3. Network connection: Ethernet. Target: Mytek Brooklyn Bridge, through USB.
The music starts playing through Roon to my Mytek Brooklyn Bridge. After a while the Roon client on ipad shows the message “cannot connect to Roon core”. After this happens there is no way to reconnect ipad Roon client to Roon core again, except shutting down the ipad and rebooting.
The Roon core PC is alive at all times and the Roon core software is running as usual. I can connect to that PC core through the network using other means, from other PCs or even from the Ipad itself, without any problem.