Sounds like I'm having the exact same problem:
(reposted)
722k receiver connected to broadband via a linksys game router. I can download video on demand and successfully set up recordings from the dish remote access website. However the "MyDVR" button on the website remains "grayed out" so I cannot manage my recordings/DVR space, etc. (I am not trying to view the programs on my DVR online since I don't have a slingbox.) Going to Preferences -> Receiver says my receiver is not online.
On the receiver, I've reset the network connection, then checked it under Diagnostics. Both of those tests report the receiver is connected. Only the MyDVR tab remains grayed out and the Preferences -> Receiver on the website reports it as offline.
This is a new system and I got everything to work a few days ago, including the MyDVR tab. I can think of nothing that changed on my end to make it fail so weirdly now.
Is there anyway from the Dish Remote Access website to get it to "look" for receivers?