Router won't accept the static IP I created for my PS4.

My internet connection is great, but in quite a few games online i'm having NAT issues and being disconnected. I play competitively, so it's beyond frustrating. I followed what i was told to do and all seemed well, it connected, was running fast. But when i looked in the router, it had completely changed the ip to something that my ps4 wont even accept. And im still being kicked. I've asked everyone, even my internet tech.. He haflway ignored me and said he didn't know how to do that or make forwarding ports..The static ip is the only thing i can't seem to get right. It always tells me "ip conflicts with so and so". Any help would be great! I'll go as far as to let somone remotely do it and help me instead of just explaining to me. Please help!