It is therefore necessary to go there to physically act on the power supply. Assuming that the best thing is always to understand why this can happen and solve the problem, but sometimes it's not always easy (for example when an atmospheric discharge blocks some devices). Some insert a timer that periodically disconnects and replaces the power supply to prevent it. Others insert ethernet relays which have an IP address and can operate in this way.
I built a small hardware that connected to the mk usb socket and using the command "usb system / power router reset-duration = 5s" allows to act as a power switch to solve the problem explained.
Since the MK's USB port is always powered I did NOT simply insert a 5V relay in parallel with its power supply, because in this case I would have, even if little, a continuous consumption of the relay coil.
I solved by entering a minimum of logic and using the NC contact of the relay, when the relay is not active, the power supply switches.
Because everything works of course the MK must be reachable
If anyone is interested I can put the wiring diagram, pc drawing components list and processor firmware so that you can build it yourself if you think it useful.