So I don't want to turn off UPNP on my router, there are other devices on the network that may become somewhat unhappy if I do that. As an experiment I unplugged the Ethernet line from the DECA and rebooted the HR34, and I don't think I've seen any disconnects in the couple days since I did that. That may be an OK short term solution, but I don't like not being able to have internet access available for it, as well as the fact that it renders my Nomad/Genie thingy useless. Providing a static IP for the HR34 prior to the DECA disconnect did not solve the problem, but I think I should probably have also tried to provide static addresses for the two Minis as well, so maybe I'll plug it back in and try that.
Makes me grumpy.