Can't install QWT on Qubes OS R4.3

Hi, I’ve been having troubles installing QWT installed on both Win 10 and 11 qubes.

I installed a fresh copy of Windows 11 25H2 on a template qube with 8192MiB of memory and 4 vCPU cores, then I disabled UAC, set PS execution policy to unrestricted, disabled hibernate, enabled testsigning, and rebooted the qube. On reboot I tried to install QWT with default opts, only disabling GUI agent, then the qube’s display froze.

I restored the qube from a clone and tried again. This time disabling GUI agent and all Xen drivers.

Now I get the following error:

Service 'Qubes RPC agent' (QrexecAgent) failed to start. Verify that you have sufficient priviliges to start system services. With 2 boxes saying Retry and Cancel. Retrying gives the same error.

Starting qrexec-agent.exe manually gives the following error:

[20260113.082110.361-6672-E] SvcMainLoop: StartServiceCtrlDispatcher failed with error 0x427: The service process could not connect to the service controller.

Starting it from services.msc gives this:

Windows could not start the Qubes RPC Agent service on Local Computer. Error 1068: The dependency or service group failed to start.

I tried with different versions of Win 10 and 11, and I still can’t get it to work.