If there is something you would like to see changed on the PXE Rep, either default settings or some behavior change, I'm definitely open to hearing about it. In this case the MTFTP and PXE spec hasn't changed, but those laptops don't work. I don't believe the problem lies on our end. I would guess Dell should be the one fixing their systems.
Again, if there is a particular setting that we are using that is outdated and needs to be changed I'm open to that. I just know that the spec hasn't changed since 1998 (TFTP) and 1999 (PXE), so it seems unlikely we have a defect that has gone 15 years without discovery and only now is showing itself, and even then only on certain models.