@limis 

I reboot APs at 12  sites using 4.1.5 every Friday at 9PM and it works great for me. By 9:02PM on Friday, I get an email of these APs reconnecting back.

Go to Settings (lower left corner, under the Admin), Services, then into Reboot Schedule, add a new one, give it a name, enable it with a check mark in the status box, specify the occurrence / time of reboot, choose the APs to be added to this reboot schedule and hit Create.

Hope this helps.