If the connection is being lost regularly within the Sonos App, then that sounds like something is getting in the way of the multicast ‘device discovery’ packets over the local network connection between your mobile and your speaker(s). There can be a lot of various reasons why this may happen, from a settings/configuration issue with your router/wireless network to settings/software on your mobile device and even a number of things in-between too, like misconfigured ‘managed’ switches etc.

As some ‘first steps’ to troubleshooting the issue, I would ensure that both the controller device and speaker are operating on the same wireless band and WiFi access point (ideally use the 2.4Ghz band with a non-overlapping channel and a channel-width of 20Mhz only) or even give SonosNet ‘wired’ connectivity a try instead, that’s if your speaker(s) support that type of network and you have the necessary dongle needed, in some instances.

Also ensure the mobile device (controller) wireless link is not being hindered by firewall, VPN, or other security software and maybe check online to see if there are are any known multicast issues with your router etc.

Hope those few suggestions help to get you started in resolving your connectivity issue, which of course, has no bearing on Bluetooth playback/connectivity.