USB Modem Not Working on Windows 11 25H2 Client

Submitted by yuki2 on #1

Hello,

I am using VirtualHere Server v5.9.9 on Windows Server 2025. A USB modem is connected to the server.

I created a Windows 11 client virtual machine on Hyper-V running on the same server, and I would like to use the USB modem from the client through VirtualHere.

During testing, I found the following behavior:

  • When the client OS is Windows 11 25H2, the USB modem does not appear in Device Manager.
  • In the VirtualHere Client window, the device status shows "In use by you".
  • When I use Windows 11 23H2 as the client OS, the USB modem works correctly and appears in Device Manager.

One thing I noticed is that the VirtualHere Client menu is different between Windows 11 23H2 and 25H2.

  • On Windows 11 23H2, there is a menu option called "Auto Use All Devices".
  • On Windows 11 25H2, this menu option does not appear.

My question is:

Is there any known issue with Windows 11 25H2, and is there a way to make VirtualHere work correctly with a USB modem on Windows 11 25H2?

I am currently using VirtualHere version 5.9.9.

Thank you for any advice.

Best regards.

 

Submitted by Michael on Tue, 2026/07/21 - 12:57

#2

When "Auto Use All Devices" does NOT appear it means the virtualhere client is probably running in RDP mode. I dont think you need to run the client in rdp mode. Can you turn that off in the client running 25H2.  Right click USB Servers->Advanced Settings->RDP Mode turn OFF

Submitted by yuki2 on Tue, 2026/07/21 - 13:24

#3

Thank you for your reply.
After disabling Session Isolation (RDP mode), the USB modem appeared in Device Manager and was detected successfully.

However, I am curious about one thing.

Why does this issue occur on Windows 11 25H2 but not on Windows 11 23H2?

With Session Isolation enabled:
- Windows 11 23H2 works correctly.
- Windows 11 25H2 does not show the USB modem in Device Manager.

Do you know of any changes in Windows 11 25H2 that could affect Session Isolation or USB device handling?

I will continue testing to confirm whether the modem functions correctly in actual use, but I wanted to understand if there is any known reason for the different behavior between 23H2 and 25H2.

Thank you again for your assistance.

Submitted by Michael on Tue, 2026/07/21 - 14:32

#4

When using Session Isolation via virtualhere - The USB Modem should appear under System Device->Remove Desktop USB Hub in Device Manager. It wont be attached to the VirtualHere USB 3 eXtensible Host Controller. Is that what you are seeing?

 

Submitted by yuki2 on Tue, 2026/07/21 - 14:45

#5

Thank you for the clarification.
The modem appears under:

VirtualHere USB 3 eXtensible Host Controller

-> USB Root Hub (USB 3.0)

    -> Conexant USB CX93010 ACF Modem

It does not appear under "Remote Desktop USB Hub".

In the VirtualHere Client window, the device is shown as:

(COM3) USB Modem (In use by you)


Please note that this behavior is observed when Session Isolation is OFF.

When Session Isolation is ON in Windows 11 25H2, the modem does not appear in Device Manager and cannot be used.

After disabling Session Isolation, the modem appears correctly in Device Manager and is attached to the VirtualHere USB 3 eXtensible Host Controller as shown above.

I am continuing to test the modem functionality and will provide additional information if needed.

Thank you.

Submitted by Michael on Tue, 2026/07/21 - 14:55

#6

You dont need session isolation in a VM. Leave that off

Submitted by yuki2 on Tue, 2026/07/21 - 14:59

#7

Thank you for the explanation.

Disabling Session Isolation resolved the issue, and the modem now appears correctly in Device Manager under the VirtualHere USB 3 eXtensible Host Controller.

I understand that Session Isolation is not required in my Hyper-V VM environment, so I will leave it disabled.


Thank you for your help.