I'm running latest 6.2.3 which again has support for onboard NIC, with MAC addr 38:XXX (as seen in BIOS). I also have Intel EXPi9301CT with MAC addr 68:XXX (as written on it).
When I plug external along with onboard and put both in grub.cfg, i.e.
set mac1=38...
set mac2=68...
I can boot, both NICs work, but MAC addresses apparently swap around, i.e. internal NIC takes 68:XXX address and external 38:XXX.
With external plugged and
set mac1=68...
only external NIC works, and it uses its own 68:XXX MAC address.
With external plugged and
set mac1=38...
again only external NIC works, and it uses 38:XXX address.
When I leave only internal NIC, nothing works.
What might e the cause and what I am to do? I guess I can keep external NIC and leave it unused, but I'd rather use it in another project.
UPD: I suspect that internal NIC drivers don't work in recovery mode which happens after any changes in grub.cfg.
UPD2: External NIC always becomes #1, and internal #2, which might explain why setting only one NIC in config doesn't work. Is there any way to reorder them?