Just an FYI,
Using Datto backup to the cloud will push outbound traffic to max out. If you have a hybrid VOIP on the same circuit but in front of the UTM, you may experience issues with call quality, i.e. the phones will sound like crap. This will persist until you shape SFTP application coming from the backup. Very important when the client is a health care provider and the Docs need to call in/out.
I tried to shape traffic manually in QoS with no luck. My failure was with trying to shape the traffic and not the application. It finally worked when I opened the Flow Monitor and shaped it there. It created a rule in Traffic Selectors under QoS for the SFTP application. Of course, you must have QoS turned on for both your LAN and WAN before or you'll get an error.
Here's the thing: Once the traffic shaping wizard creates the rule, I don't see a way to change the amount of traffic allowed. You have to delete the rule and re-create it with different numbers. Not sure what's up with that.
Just sharing the good times that were bad phone quality with offsite backup.