Hello and thank you in advance for any help you can give me!

i recently purchased the M5 to use a a router to get better coverage throughout my house AND to take advantage of the parental controls as my Greenwave C4000XG (CenturyLink fiber) is terrible at both. Got M5 set up easily, but then realized that it was causing some issues. Contacted TP Link through chat (ended up spending 3 hours with no resolution) and was told to put my M5 in access mode. Still had issues with devices not connecting completely (e.g. laptop wouldn't connect to websites like Walmart or Target but would connect to Amazon; wouldn't connect Yahoo, but would connect to Google) but was thinking of trying a reset and starting again.

 Here's my problem: my Greenwave is a modem/ router combo. From what I've read since then, M5 won't work as a router with that device (probably why I was having issues yesterday). But then I've read that using it as an access point will disable the parental control functions- I NEED the parental control functions- it's the entire reason why I bought the mesh system to begin with! Is there some way to keep the M5 and still use it as a router? Maybe log into my Greenwave and turn off wifi after setting up the M5 again? Or use M5 as an access point AND keep the parental functionality?  If not, is there ANY mesh system that will work with a modem/ router combo for what I need? I can deal with reduced coverage in some spots in my house- what I can't deal with is two teenage boys who currently have free reign of the internet! Any help would be GREATLY appreciated!