Disclaimer: This information is provided as-is for the benefit of the Community. Please contact Sophos Professional Services if you require assistance with your specific environment.
Sophos UTM can be installed with a normal USB drive but this is installation process is not officially supported.
Prerequisites
Steps for UTM installation with normal USB drive
Insert a USB drive and start the Rufus utility. (Rufus will auto-select USB device)
Format the USB drive.
After that choose the Sophos UTM ISO file (Rufus will select the appropriate settings)
Click on Start to create the media.
Once the process is completed, close Rufus and remove the USB drive.
Insert USB drive into the DUT and power on.
DUT will automatically boot with the bootable USB.
Sophos UTM installer will start and display the black Welcome screen. Press Enter to start the installation.
At the blue Introduction Screen press Support option to stop the countdown and press back option.
Press Alt + F2 this will switch you to a console screen.
At the console prompt, mount your USB drive with the following command: mount /dev/sdc1 /install
Note: USB will detect as sdb/sdc or any next letter
Press Alt+F1 to get back to the installation screen and press "start" and continue the installation.