Makes sure you set the time blocks, Have to do every single block for every single day manually.
Option two and best option, take kids phone away at bed time as it doesn't stop them from playing games all night or accessing internet with the Phone using up data plan. Thats what I had to do with my 16YO Son (mine didnt get cell phones until their 16th Bday and I wanna puke every time I see an 8YO with a cell phone). Every night at lights out Id receive the scowl when I held out my hand without saying a word, He knew what that meant. Unfortunately your router cant shut down their internet access through cell provider. Kids don't have cable boxes in their rooms, only netflix etc and that I can shut down at bed time as it doenst have a backdoor with a different way to connect.

People complain about cyber bullying yet they give their young kids a wide open window for it 24x7 and the dark web when they hand them a cell phone. I have very strong beliefs in this. People turned to electronic babysitters and turned their kids into lazy idiots. The along comes Michelle O mandating the maximum calories in school lunches because of the obesity epidemic. Its not the calories Michelle! Its the fact they sit on their butts all day with electronic devices, gaming console, or TV. When I was growing up and there were none of these devices kids were ALWAYS out and about playing burning those calories. Obese child was like maybe 1 out of 1000. Now its more like 1 in 5. Coincidence? I dont think so.