I have a wireless four-camera Arlo Pro security camera system. I have a 100 mb/sec wifi plan.

Every time I see a news story on TV that shows a home security video, it’s clear as a bell. The images with my Arlo system are substantially lower quality, even if my video settings are at the high quality level.

Any ideas on what might be going on?

Not sure of what your issue is. All I can say is the image quality on my Arlo Pro cameras is certainly acceptable, even after I changed the battery life setting to maximum.

Might be a faulty piece of equipment, I'd give them a call.

The system were set for my grandmother is clear, both day and night.

Are you comparing Arlo Pro to Arlo Pro 2 cameras??
Arlo Pro is 720p
Arlo Pro 2 is 1080p


Getting ready to order a system for my mother for Christmas. The in-laws recent got a system and I am super impressed with the quality and ease of use.
Ease of use is what my mom needs so that is why I am going with it.

Security cams like any other camera is all about the physics of light.
Not know the scene and lighting it is hard to say but it is always possible that there can be a hardware malfunction.
IP resolution has less to do with that the lighting conditions.
Also take the shipping plastic off the lens too.

FWIW, Arlo picture quality under normal circumstances is adequate.
A plus for the Arlo series is the ease of setup but a miss on some functionality as well as battery issues/life.
YMMV