This Admin mail occur every hour.
Web Application Firewall not running - restarted
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HA Status : HA SLAVE (node id: 2)
System Uptime : 0 days 2 hours 49 minutes
System Load : 1.18
System Version : Sophos UTM 9.170-21
Please refer to the manual for detailed instructions.
Release 9.170-21 HA Cluster running on Hyper-V V3 (Server 2012)
I think thats a Problem with the Drivers. Because Hyper-V V3 Drivers not present in the UTM. I had similar issues in the latest official Version.
I just hope that the programmers can implement actual Drivers for the actual Hyper-V Version.