@MNS-Online.net 

Hi,

Do you mean Internet access for things like web browser and all other Apps is successfully being blocked on her device and solely WhatsApp is somehow able to get Internet access?

@woozle Yes, internet access so during the no internet schedule, I tested browser, Instagram and ALL do not work because the internet is blocked. The wifi connection on my daughter mobile is connected, but no internet (display "Connected without internet") and WhatsApp message are going through.

No, she was not getting internet and yes, I had the device with me and did some tests and WhasApp works.

@MNS-Online.net 

I haven't heard anything in this regards about WhatsApp yet, but I know that Skype was once capable of getting around firewalls by using Skype clients on other non-blocked devices within the same network as a gateway, until Microsoft abandoned that protocol several years ago. If you are interested to know more, then google for Skype+supernodes.

Anyway, if you want to rule out that WhatsApp isn't maybe doing something similar, then do the following test. During your daughter's offline time temporarily take all other devices that are running WhatsApp (like yours, your wife's, etc.) off your home network and then check again if your daughter's WhatsApp still works.

Other than that, it could still be a flaw in the router's Parental Control. 

By the way, does your daughter's device have an active SIM card in it?

@woozle OK, I will try that tonight.

She does havean active SIM card with no data (plan).

@MNS-Online.net 

I think your doughter is using this WhatsApp Plus because this is a modified version of WhatsApp which allow user to use WhatsApp with it's amazing features.

@xavier221 

I checked her and she's got the official WhatsApp from Googlle Pay Store.