Setting up a bridged connection in Linux/Lubuntu

I’m trying to set up a bridged connection on my Lubuntu machine, on which runs Roonserver, hoping to achieve some SQ-gain (see: here)

No problem changing /etc/network/interfaces, as specified below, albeit with other designations for the bridged ports:

auto lo br0
iface lo inet loopback
iface br0 inet dhcp
bridge_ports eth0 eth1

It works, but only for a short while: after some time my Roonremotes (android) can’t connect to Roonserver anymore. Only after rebooting I’m able to connect again to Roon, but (again) only for a short time.

Any ideas what’s causing this behaviour? Solutions?

Thanks for helping out!