Hello@RedX1 I also picked up 2 8259CLs from him on ebay, and also using MD71-HB0, but I'm having some issues -- see post: https://forums.servethehome.com/ind...md71-hb0-datto-siris-4-bios.43158/post-427234 -- do you mind sharing versions / files of BIOS/BMC of your working setup?
Just like you, I found my motherboard arrived with zeros for nic ip addresses, I too used the same method to restore them.
I updated the BMC to the latest Gigabyte firmware, not the old Vertiv 1.98. by USB. I then update the Bios to R20 using the BMC.
This caused the MB to again wipe the IP addresses of the nics.
I have not updated it since.
I am using Windows 11 with no problems.
I hope this helps.
Good luck.
RedX1