Reboot over ssh

I'm trying to reboot a Teltonika RTU950 using ssh. I can log in as root via ssh and then reboot the router fine. However if i try to send the reboot command over ssh it does not work. ssh root@routerip 'reboot' This returns the error: ash: reboot: not found I've tried using shutdown -r instead. Also tried using absolute path. Always gives me the same error. To be noted that the error says: ash: and not bash:. The router runs on a linux os. uname gives: Linux Teltonika-RUT950.com 3.18.44 #1 Any idea what could be causing this?