Did you have give them a call? I got fast respons when I emailed them.

I contacted TP-LINK support before, they said there is no big difference between V4 and V5.

You can email TP-LINK support to check it.

Hi, check the System Time of the router, it shows 3rd Jan 2016 on your second screenshot, it should be wrong. Go to System Tools---Time Settings, make sure the router has correct time.

Where do you see the DHCP requests? And does it have any trouble in your network?

Hi, that's the settings on the Fast 5355, you can connect a computer to the WAN port of the Fast 5355 directly , make sure you can get internet access on the computer. Then connect the D7 to the WAN...