The main Deco is on default router mode or AP mode?

Actually you can either replace your existing router with Deco(as router mode with DHCP server) or connect the Deco to your existing router(set Deco as AP mode), here is the FAQ to set AP mode:...

That is also what I want to say, I don't see such button to add a specific time in parental control on the Deco App, it seems that we can only modify the settings manually.

WiFi will disappear? that is so strange, you may check whether the firmware is the latest one

Hey guys, found the link for you, this is the beta firmware the tp-link support provided for my 5GHz disappearing issue: http://static.tp-link.com/Archer C7(US)_V2_170117_beta.zip

Yeah, it seems a beta firmware which fixed my router from 5Ghz signal disappearing. You may call them and get the beta and have a try. Seems the same issue.