Circle has evolved much more to even pn the 4G service. I have my own review of it that I can share. It is actually not controlled by DNS but rather by device. I had it for two months before the 4G service as a trial and worked as intended but the hardest part was to control it remotely, I needed to be at home or my wife and the Android apps wasn't that great. I would think Untangle can do the sam as well. I can share my review if you want.
To be honest I am using OpenDNs right now.