So, something really weird's going on with MDT.
On this one computer that I'm trying to re-image, it has exhibited multiple weird behaviours, like, initially, it took me to the password screen, I entered my credentials, and after that, it just rebooted.
During other attempts, it either reboots right after it loads the last file or after it gets to the MDT background, or at various other random bits during the process. I think I managed to only get it as far as the credential prompt once, but not past that at all.
Since this is so completely random I thought of posting an other question as other ones I've found online don't match my setup.
WDS runs on a 2008 R2 (don't ask why), and, I did manage to do an F8 after getting into MDT once on the affected machine, and, an ipconfig showed that everything was fine, as, initially, I thought that this was a network driver issue.
Since it doesn't seem to be, I'm completely stumped, as, we've rebuilt dozens of other PCs about a month ago and everything was fine. Those were re-imaged over UEFI PXE boot though, but, for this machine, that doesn't seem to work at all so I have to use the non-uefi PXE boot.
(the WDS MDT image is windows 10 64 bit)