Hi,
we can update to 9.1.2057 using Software Installation (ESET Endpoint Antivirus) in ESET Protect.
This was ok but the end users get a lot of warning pop-ups whilst it happens which we didn't see on moving from 8.1 to 9.0.
If "auto-update" capable 9.1 will not appear soon then we will look more at this method so we can update from 8.1 before end of November.
Perhaps 8.1 full support might be extended until issue is fixed?