i bought the same router model and having same issue can't get into internet.
checking the connection status, it shows connected and obtained IP address but it start from the range 172.x.x.x instead(always this range no matter how many time reconnect).
checking traceroute it stop after enter tm network. it sure look like connected but can't get internet.
then i switch it back to my previous router L7 and it's working and able get internet, checking the ip it's not 172.x.x.x instead 203.x.x.x

still checking how to resolve this issue

Hi, I am one of the victim here, bought a dlink 816L recently, wifi okay but not the internet connection.
can anyone share the solution to this?
what is this firmware reflashing? it was stated easy to use in the user guide.
thank you