Odd Behaviour Reconnecting Monitor to 5070 (when logged into VM)

Good Morning All,

I wondered if anyone has seen this behaviour before? We're currently liaising with Dell Support, but intrigued to know if this is just impacting our 5070 terminals.

In our Horizon VDI environment (Horizon Agent 7.13), we use Dell Wyse 5070 terminals. The majority are running ThinOS Version: 9.1.4234 // BIOS Version: 1.12.0 // Horizon Client Version: 2106.8.3.0.18251983.5. As well as a bunch on ThinOS Version: 9.1.6108 // BIOS Version: 1.15.1 // Horizon Client Version: 2111.8.4.0.18957622.6.

I'll explain the behaviour using a scenario.

I have 2 monitors connected to my 5070 (via DisplayPort). I login as normal and connect to my VM.

Whilst logged in, my 2nd monitor (secondary) gets disconnected by either:

+ Turning off using the power button, or

+ Accidently dislodging (removing) the power lead or DisplayPort cable.

When the 2nd monitor disconnects, the VM adjusts its display for one monitor as expected.

We then power back on/ reconnect the 2nd monitor, but instead of the VM detecting it and spanning the VM across both displays, the 2nd monitor just displays the background wallpaper of the 5070. For your VM to use both monitors, we have to tap the power button to disconnect from our VM session and login again (or restart the Wyse).

Interestingly, when that happens, if I then turn off the 1st monitor (primary), the 2nd monitor (secondary) happily displays your VM, even though it was only displaying the 5070 background wallpaper. It's as if the 5070/ Horizon Client decides that once a monitor has been disconnected, it will only allow you to have a single display for your VM.

Hopefully that makes sense, but if not, the below might be more useful. Any thoughts?

Have a nice day all!

BOTH SCREENS ON (PRE-LOGIN)
Primary Monitor - displays Horizon login and Wyse background wallpaper.
Secondary Monitor - displays Wyse background wallpaper.

LOG INTO VM
Primary Monitor - displays VM.
Secondary Monitor - displays VM.

### WHILST LOGGED INTO VM ###

TURN OFF SECONDARY MONITOR
Primary Monitor - displays VM.
Secondary Monitor - off.

TURN BACK ON SECONDARY MONITOR
Primary Monitor - displays VM.
Secondary Monitor - displays Wyse background wallpaper.

TURN OFF PRIMARY MONITOR
Primary Monitor - off.
Secondary Monitor - displays VM.

TURN BACK ON PRIMARY MONITOR
Primary Monitor - displays VM.
Secondary Monitor - displays Wyse background wallpaper.

DISCONNECT FROM VM / RESTART 5070
Primary Monitor - displays Horizon login and Wyse background wallpaper.
Secondary Monitor - displays Wyse background wallpaper.

LOG INTO VM
Primary Monitor - displays VM.
Secondary Monitor - displays VM.