According to DIRECTV,
about half of the issues where customers see Error Code 775 on the screen are due to unplugging the power inserter. The power inserter is the grey or black box that powers your dish, and it looks like the image you see above. The most common cause of problems is people intentionally unplugging it to plug in something else.
Avoid this sort of problem by training everyone in the house that they cannot unplug this device or it will cause problems for everyone. Even if you're not watching TV, it can cause you to miss recordings or cause your receivers to report errors that aren't really there.
If the power inserter is plugged into an outlet that you'll need, it's ok to unplug it for a short while to move it, but be careful not to kink or twist any of the cables attached to it. Also, you may need to reboot your DIRECTV receivers to get them to work again after unplugging the power inserter, and it can take up to 5 minutes for the satellite dish to function properly after it's been unplugged.
If you're curious about other DIRECTV error codes, check out our comprehensive list!