Not quite sure what you mean by ‘costs me a lot’, but there should, in general, be very few issues in maintaining a connection between the Beam and the Sub. It should never require any reconfiguration at all.

So, a few things to check. First, make sue the radio/WiFi is turned on for both the Beam and the Sub. The Sub actually connects to the Beam on a hidden 5Ghz network, so both radios should be turned on.

Next, look around both devices for potential sources of wifi interference , particularly, but not only in the 5Ghz range, as this can affect the connection between the Beam and the Sub.

If it still is having trouble maintaining a connection, unplug both the Sub and the Beam from power, and reboot your router. Wait until the router has finished rebooting before plugging the Beam in to power, followed by the Sub.

At no point in time should you factory reset either device. This usually doesn’t help anything, and always deletes data store on each device that might help Sonos figure out what is going on.

Finally, if none of this helps, I would recommend that you submit a system diagnostic, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

One of my first steps would be to force close and restart the controller.

Regardless of the controller’s opinion with respect to SUB being present, does SUB play?