I just want to say for the first week, my gaming experience was the best I've ever had, simply perfect. Then randomly after a week or so, it has gone dire/unplayable. My download and upload speed are the same as is my ping, nothing else has changed. Iam experienced and have enabled DMZ etc, opened all necessary ports for the game I play. The only thing I can think of is that virgin have either put me on traffic management, or have changed some other setting. Any ideas guys? Thankyou in advance
For what it is worth using DMZ to allow you to play games is like using a sledge hammer to crack a nut. It's imply overkill.
I do however accept that the SH3 (which is what I imagine you have got) isn't the best at network so would advise using the SH3 in modem mode and then using a good router to handle all the other networking tasks such as DHCP/Port forwarding and so on. A properly configured router with port forward/UPnP should eliminate the need for using DMZ completely. For instance I have my devices behind a Linksys WRT1900ac that is doing all the NAT, port forwarding and so on, with it configured correctly I have good gaming experiences on PC, PS4 and XB1 (NAT 2 for PS4 which just means your PS4 is sat behind a NAT device that is configure correctly, Type 1 being directly connected to the internet with no NAT and Type 3 being behind a NAT device that isn't correctly configured).
Apologies if you feel this is something you already know but it's better to start from the beginning when troubleshooting these issues.
Set up a Broadband Quality Monitor here and that will highlight any issues during certain times of the day etc, make sure your gateway responds to ICMP/anonymous traffic otherwise you'll just get a solid red graph as it will be dropping the pings.
There's also a thread relating to SH3 performance because of the chipset it uses. That is worth a quick read too.