Recently, I got rid of my Sprint 3G/4G Overdrive access point and replaced it with a Verizon Jetpack 4G LTE access point. This thing is really fast and seems to get great coverage in a lot of place. However, the other day I started to have problems with it disconnecting and reconnecting repeatedly (on the order of 2 to 3 times per minute). Each time it disconnected, my VPN connection (if I was using it) would drop and in general the device was unusable.
I did some poking around and noticed that the device enables IPv6 by default. Since my machine is configured for DirectAccess (which uses IPv6 transition technologies) I wondered if turning off IPv6 on the device might help. I figured that it couldn't break anything since nothing on my machine would expect IPv6 to be available, so I went into the configuration and disabled it.
Sure enough, since I made that change, my connection has been rock solid and the disconnections are gone. I am not sure what exactly was happening, but now I can connect to the Internet, DirectAccess comes up as expected and life on the road is good again.