I suggest from your MRDVR STB you go to
Menu
Customer Support (at bottom)
In-home agent
MRDVR Troubleshooting
After a few moments waiting for this to load verify that your DVR is primary device and its activiated. It should be the device you are currently doing this on.
From the other room STB's make sure you can access the channel guide and video on demand.
Try rebooting all devices
Try rebooting the router
From the STB go to:
Menu
Customer Supprt
Self Diagnostics
Start
Review the output pay attention to the last, MV DVR Client. See if it passes these tests.
Report back the results.