I use Wyze cameras. I believe they've come out with a wireless version but my coop is wired so I use the plug-in version. I bought 4 cameras for under $100 dollars. I did have to get a better router to get the wifi signal out to the coop. My coop is about 100 feet from the router location in the house.
I can check on the birds whenever I need. When on vacation, I actually logged into the coop cam one night to talk my nephew through getting a broody out of the nest during nightly lock up and head count. You can speak through the cameras too.