Alright, I'm ready to start diagnosing your guys' issues. I only used my home WiFi and never connected directly to the Media Link HD receiver, so I set that up and then disconnected. I am in a basement (that's where my room is), so I frequently get data drops but I always reconnected after a few minutes or just going upstairs. So, are you in a poor signal area? Have you updated your profile and PRL? Maybe try rebooting? Have you updated the Media Link to its latest firmware? I don't know what to tell you, as I tried switching between both methods of connecting to the Media Link box and couldn't replicate a complete loss of data; mine always came back on. I'm running the latest viperROM, if that makes a difference, but it shouldn't.
Edit: Hold up. When connecting directly to the Media Link's network, you lose all internet connectivity, as the phone's WiFi is connected to an internetless network, but still, you should reconnect to 3G no problem after turning off WiFi. I get the error message a couple times, but my 3G always comes back on.
Tapatalked from my shiny new HTC Evo LTE