Response 4 port gateway - one universe blinking

I'm wondering if anyone knows what would make just one of the four ports start blinking. The other three ports are outputting DMX fine, so it's not a loss of connection to the console. We have two Ions and a Geo on the network. Disconnecting the Geo seems to eliminate the problem, which is odd because it's just backing up with all its output settings set to off. It's happened on more than one Gateway, though not at the same time. What, other than a loss of network connection, would cause a gateway to think one universe had lost DMX? 

Related