Unable to upgrade from Windows 11 23H2 to later version

When I try and do the feature upgrade to 24H2 2026-05 on a Windows 10 era Dell PC  (let's not get ahead of ourselves with 25H2!) the upgrade fails and rolls back.

setupdiag points to 

Error: 0xc1900101-0x40017 SetupDiag reports rollback failure found.

Last Phase = Post First Boot

Last Operation = Ensure suspended services are stopped

Error = 0xC1900101-0x40017

and googling suggests this is likely down to a driver. The PC in question has some realtek drivers which are seen as problematic but it is not clear what the resolution is there.

How can I diagnose WHICH service or driver is causing the problem?

Thank you

Mark