My nat type on cod was Moderate but I YouTube some stuff and this guy told me to enable dmz on my router and then put the ip of the PS4 in and apply the changes. I did that and great it worked, it has from moderate to open but my question is, is enabling DMZ bad? I seen some people say that it is a bad thing to do. Thanks
You are exposing the PS4 to the Internet without any of the protection a router can provide e.g. firewall. With a console the risk is minimal, as they are fairly locked down, it is not recommended for a PC.
I have managed to play games online for years with Type 2 or Moderate NAT on my PS3 & PS4 so I have never seen the need to go for Open NAT. Most guides I have seen say that Moderate is the best option as you can game OK and are minimising the risk of exposing a device to the Internet.
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong If my answer solves your problem please mark it as helpful as it may help others My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.