Re: does DMZ will improve gaming on PS4?
If the game is otherwise working fine and your network is working properly setting your PS4 into DMZ will not help in any significant way.
I looked up the router and it looks like it's a 4G LTE router. The latency variation is most likely due to the quality of your 4G connection. The next most likely is the quality of your wireless internet to your PS4, you can try using a cable instead to rule that out.
