I unregistered the device and registered it again and it started working. However with this operation we loose all backups for the previous device registration and also all statistics. Seems like a workaround rather than identifying and fixing the problem itself. What can cause these issues for a device that has been operational for years?
This issue can occur when RMS is unable to validate the rms_id file.
It typically happens if the device is re-registered in RMS and then a factory reset is performed immediately afterward.