I have the same problem with my Fireface 800 under Windows 7 Ultimate 64bit

I use my Fireface800 in a daily routine under Win7 Ultimate x64. My setup until Dec 10, 2021 was Firmware 2.77 and Driver 2017 3.123. Suddenly in Dec 11 my fireface didn't go online. I have made lots of tries changing fireware cables, removing the OHCI IEEE1394b card etc. The problem does not seem to be the IEEE1394 card. I also tried multiple times to reinstall the drivers the 2014, 2017 and 2019
Brifly my main problems are
1. Win7 Ultimate x64 does not detect the fireface 800 on boot so I can only "put" the fireface in the control panel if I make a "Legacy installation" anyway in that case I get a yelow triangle with an error 10 and there is no way to solve it
2. I also tried to launch the fireface_fut.exe but since the FF800 does not go online and I always see that red ligh on, that .exe does not do anything, no dialog display, nothing. Anyway this is a detail.
3. I have thought to a problem of the FF800.... but connecting it to a minimac, it seems to function correctly so I can't exit from this problem.

At the moment I have the latest 3.125 drivers correctly installed.
My main question are: how can I get the FF800 be automatically detected (PnP) by win7 Ultimate? Is it normally (in your experience) a functional solution to install the FF800 as a legacy device and then installing the driver or should windows7 absolutely autodetect the RME 800 on boot/win start?
I have tried a dozen times but PnP does not detect the fireface

By now I am sure that this is a software problem it seems that the driver doesn't load even if it is there.
I also tried to look for a restore point but I haven't find a restore point prior to the problem
I think the solution could be in forcing the system to load the driver at the startup or at the boot
this is a thing possible with winternals 2007 erd on win XP but winternals stop to 2007 while win 7 ultimate is 2009
and I have no Idea about how to do that task because I am not so brilliant to find and modify the right a register key in win7 ultimate

I would like someone  could explain how to solve error code 10 on the Fireface (win control panel)

About the cause: it seems that sonmething corrupted the capability of win7 to load the driver even if it is there
and / or to detect the fireface 800 with PnP
The cause could be a electrical interruprion or even a windows update failure.
Anyway it is such a bad thing to know the cause and  not the solution!

Looking for your help, thanks
Max

Yes, same cable.  I am absolutely sure that both fireface 800 and cables have no problem.
Fireface 800 drivers and Microsoft O.S. are the problem (since it is way difficoult to have drivers problems on a apple IOS)
I don't understand why RME (and its driver developers partners) in many years didn't provide a way to easily install the drivers and completely uninstall them. When I say uninstall them I mean automatically deleting every single file in the hard disk and every single entry related to the fireface in the windows registry.
It is really frustrating loosing days of work running after this kind of problems. You can believe me when I say that you should question your software experts about this error 10
because I can't believe they didn't hear about that error before. If you can get an anwer please let me know.
I know what error 10 means in general but ordinary advice didn't work (roll back, updates etc.)
Otherwise and hd format an total "universe reinstall" is the only solution remaining on that system. (And on many different microsoft systems for what I see).
If you want a simple question well it is here "what should your customer do when the driver gets corrupted and refuses to load?" focalize on this... not on the causes... because causes sooner or later will happen!
Your problem is to provide a solution. The solution is providing better drivers, better install and better uninstall procedures.
And of course to know what your customer is talking about. That's half of the solution either.
Kind regards.