Dave, so I went down to the theater with the intent of trying a different ethernet port on the 8801. Before getting to that, I was playing around with the Roomie Remote a little more. I have the 8801 set up via IP control/DHCP as previously stated, and also via an IR connection as well via the "Flasher" input on the back of the Marantz. I was trying both and neither worked. After going into the "Edit" mode of one of them, I received a message from Roomie saying that the DHCP IP address was automatically updated within Roomie.
As soon as I cleared the message, both Marantz remotes worked perfectly. So, it turns out that it is apparently a Roomie issue.
I think a fixed IP address would probably permanently address this, but I don't know much about how that works (do all my IP devices on the network have to use fixed IP addresses if one of them does?).
Sorry for the OT post, but I wanted to give you the courtesy of a response. Thanks for chipping in with a suggestion; I really appreciate it. I'm going to take this over to the Roomie thread on AVS' Remote Control forum.