I think I figured out at least part of my problem. The PCB that I am using, dated Dec 2011, appears to have the pinout of the Ethernet Jack incorrect. The PCB was fine for the kit that I purchased, which was the sprinkler expansion board. My error was assuming that I could then upgrade to the full board later by adding the missing components.
My next step will be to remove the Ethernet Jack and see if I can cut the existing traces so that I can jumper wire the board to the correct configuration.