I've had the same issue with my two whites. Suddenly one speaker became silent. I cut the power to the speakers but that did not help. Then I clicked three times in a row on each speaker (some kind of restart) and then set them up again. And after awhile they started to play in stereo. Long press is reinstall the whole system. Scroll down to the end of the page for more info
More info here: https://help.devialet.com/hc/en-us/artic...om-Premier
More info here: https://help.devialet.com/hc/en-us/artic...om-Premier