Hello@Rogerrrr, welcome to our Sonos Community!
I’m glad you are enjoying your new Sonos. Thank you for the kind words and feedback.
Please have a look at the following Support Article Pair Sonos Era 100 with Bluetooth.
Era 100 has an Idle Auto-Disconnect setting which will disconnect your Era 100 from a Bluetooth device after 30 minutes of sitting idle.
This setting is off by default, but can be turned on in the Settings tab under System → Era 100 → Bluetooth → Idle Auto-Disconnect.
Make sure you’ve not enabled “Idle Auto-Disconnect".
After your Sonos Era 100 disconnects, what happens when you switch the mode to Wi-Fi from the button at the back of the speaker and then back to Bluetooth mode?
At that point the Sonos Era should automatically reconnect with the previously Bluetooth-paired device. If it doesn’t, I recommend you submit diagnostics and contact our Sonos Support for some live troubleshooting.
I hope this helps.