Everything used to be ok until recently that a mac mini on a child profile stopped connecting to the internet when added to the profile. If i remove it, it works fine. 
there is no settings on the profile that specifically blocks this device. I even re-created this profile (removed the old one). 

I guess the problem started when my child played around with MAC address on his machine and I blocked or added those new ones to the profile. I have deleted all old Mac machines tracked by tp link router, but the problem still persists. 
 

i am out of ideas where to look into and how to done this problem. Please help.