We are experiencing this issue with Horizon Client and ThinOS thin clients and it appears to be on a non-graceful disconnect. Also occurs on external clients coming in through UAG and internal clients pointed to Connection server direct.

* Problem is VERY intermittent

* Horizon 7.9 with VM's on Horizon agent 7.11using Blast

* Horizon Template VM and pool video settings per best practices and Tools/agent/UEM installed in correct order

* The VM is accessible through UNC and management tools

* Windows 10 1809 LTSC