Older boxes' ethernet permissions have expired and they can no longer connect. Other boxes will suffer the same fate as time goes by.
Only the oldest have this issue, and all have had service for much more than 12 months.
Korean Developer

Spider team

FM hardware boxes - NOT WORKING - error code (0)
RM hardware boxes - WORKING- login says CONNECTED

Boxes with FM Hardware are now blocked from connect to the Ethernet server.