Have you reach for Symantec? If so, have they provided a reason why our driver is being regularly blocked by their software?So I want a solution that is working now, I have done all the usual things you suggested.
If we know why the anti-virus (AV) software blocks 3dxsrv.exe, we may have a change of modifying our driver to work-around the AV block.
Also, have you tried moving one of the systems to an AV solution from a different vendor?