Hello Nick, I would concur with your statement but forgot to mention that the gateway also stops resolving if it does not connect to the cable? I am waiting for the provider to install the cable wan setup at that location, in anticipation I was configuring the gateway yesterday and ran into this problem.
I also have tested a pppoe dynamic configuration but not static. I was able to test multiple combination with a pppoe dynamic ip's configuration, but did not encounter the above problem. Note: I am also aware of the multiple ISP issues but in this case all the connections are from the same ISP but thanks for the heads-up.