Ubuntu Server 22.04 and Proxmox 7.1 has non-free firmware as far as I know. The only problem I had with Debian was ethernet drivers because it is Broadcom.
Also what do you mean by āI would probably start disabling any devices I can and see if compatibility issues stem from any of those.ā
Iām just guessing at this point. I meant like disable peripherals like USB, serial ports, Ethernet, RAID cardsā¦ whatever you can. But again itās just based on some problems I had like āThis one time, I couldnāt install PFSense until I disabled RS232ā.
it looks like GRUB has a bootloader issue with the R710. it is fairly easy to fix but it would be best for you to watch one of the YouTube videos. as stepping someone through the process via forum posts would be time consuming.
that guy has several videos on the R710
In the video he made with the ID of Fld3BCE6h7c and shortly after 5:15 (I canāt post links) he has no problem, but is running 6.2 so I will try that version then try an upgrade if I can.
Where is your source for āGRUB has a bootloader issue with the R710ā
there are several similar forum posts on the wibble about R710 not correctly locating where to put GRUB. i suspect it has to do with the PERC, but thats a guess.