This article shows how the SonicWall switch can be restarted from the firewall UI.
NOTE: The SonicWall switch should be in a connected status to send the reboot command from the firewall UI. If it unreachable, the reboot will fail. You would either need to login to switch UI and restart or power cycle the Switch manually.
To reboot the switch from SonicWall UTM GUI:
Navigate to MANAGE | System Setup | Switch Controller and Overview tab.
You can perform this action from Physical or VLAN view tabs.
Click on the three dots next to the switch and select 'Reboot switch' option.
The switch will go into rebooting state and come back up as connected within 45-60 seconds.
You can check for the uptime of the switch by navigating to MANAGE | System Setup | Switch Controller and Switches tab. The Switch tab has Uptime listed.