This is a bit of a stretch, but your problem sounds slightly like what one might experience if one cloned a DietPi copy and installed it on a 2nd devicei. If your devices are Roon Ready then they must have some form of the Roon bridge and if both of your devices are using the same Roon ID then that would be a problem. It wouldn’t be the first time, that a vendor ( in this case, the vendor being Naim) installed Roon bridge from a cloned copy (assuming, incorrectly, that there would be only one of their devices in any one given system) .
See the discussion in this thread and elsewhere -