For what it is worth, I had a smoothieboard I was trying to connect
directly to my computer, and no power on earth seemed to be able to
make it work reliably with DHCP. I statically configured the IP, and it
connects every time with a direct connection. Never did figure
out that issue, just leaving it static now that it works.
(It would talk via DHCP about one in 10 times I powered it up).