It was plugged into a DLINK DGS-2208 Gigabit switch, which is plugged into a 100Mbit switch, which is plugged into a WNDR3700v2 (running the Bismark build).
Hypothesis: it might have problems if it sees ethernet pause frames. I first became aware of pause frames when I saw them in a wireshark capture I took off this switch last fall.
My laptops dhcp off this switch just fine, FWIW.
I was unable to reproduce in a similar environment.
I’ll do a more systematic round of tests in the morning.