When we had cable, our TV and DVR both had Aspect buttons. It may be in your TV setup menu too.

But there may be one under tools of menu.

Such as if you had a 4K-capable DVR with a 1080p TV, and the DVR was set to output 4K. Or your TV got set to 720p mode while the DVR is still outputting 1080p.

These are less likely, but conceivable scenarios ... an issue with Aspect is more likely ... you may have a zoom mode enable on the TV. A clue to this would be whether other sources appear cut off as well (like a cable box or dvd player or whatnot ... if the TV aspect was zoomed, it would likely be for all sources ... though not all TV's are like that).

Edit: look for buttons on TV remote labeled Zoom, Picture, Aspect, or a screen icon w/arrows pointing outwards away from the screen. Or check menus ... normally it's on the remote. Note this is PROBABLY on the TV remote i.e. the one that came w/the TV ... but could be adjusted on another one if you programmed other remotes with the code to operate your TV directly. TV remote is your best bet to fix it even if it didn't cause it to begin with.

The TV looks right, but I could be missing part of the picture around the edges and not realizing it. I'll start with the TV remote and see what I can find.

It was normal when I first started using the DVR with Netflix, so I know it can be right. I think it's one of those things where I punched a button by mistake and didn't realize what I'd done. (I do that with computers all the time, like the notebook I'm typing on right now.)

There is a button labeled P.size. Could P be for Picture?

Try that ... there's often multiple modes with repeated presses ...

I'll be sure to remember if this happens again.

It was the P.size button on the TV remote. I had to hit it a couple of times to get it right. First, it gave me an image that was too small, but the second time, it came out just right.

It had to be something to screw up easily because I hadn't been messing with the settings. This little button is right at the bottom of the remote, where I could bump it by mistake.