Alice,
Two onboard nics, Intel, eno1 and eno2
If either of them is set to onboot then network won't start.
one error message says :bad vendor preset disabled
This bug report from the upstream vendor (RH) for RHEL 7 might help in troubleshooting what's causing the error message:
See: https://bugzilla.redhat.com/show_bug.cgi?id=1399448
Apparently something "broke" (changed) between 7.2 and 7.3 in how the networking scripts bring up the interfaces.
Cheers!
Simba Engineering