NAT Problem

[Aiden2k13]

Hi , my PS4 is connected to the router via wired connection but when I am testing my internet connection , it is obtaining IP address just fine, getting Internet status also fine but as soon as it gets to NAT, it shows FAILED. It gives Error NW-31374-8 . I have set the PS4s IP Address to DMZ in my router but still
I have also forwarded specified ports and setup Static IP , but nothing is working.
I am getting NAT Failed.

I am using Linksys E900 router.

Can anyone help ?