Greetings, @sergi.ctrl4 ,
Welcome to Teltonika community!
It appears that the user account you’re currently using doesn’t have sufficient permissions to run that command. The root user has full access to all functions, while the admin user operates with limited rights - including restrictions on executing SSH commands. Please try logging in as root, and you should be able to run the command without issues.
Same topic was discussed here as well: Reboot of RUTX50 via unix is not working
If you have any additional questions, please don’t hesitate to let me know.
Warm regards,
V.