Shouldn't a simple
set up the network on the Atom board.?
Then on the Atom use the ftp command I gave for a test download.
Don't use the laptop at all. The whole point of my proposal is to use just the Atom OBSD board behind your D-Link router. That way OBSD doesn't have to do the possible, PPPoE and NAT stuff.
And for this test just trust the D-link firewall and disable pf. Keep things simple