How do you make an open NAT type

[MasonLol]

Ill try to explain the situation as best as I can. I have 30mbs DL speed, I play League of Legends and my dad plays call of duty on PS4. We are having problems lagging when we are both playing. We have a cheapo router and I just bought a D-link AC1750 dir-868L router. With the old router whenever my dads NAT type would go to moderate or strict he freaks out and restarts the modem until it goes back to open... If anyone plays League you know you just cant restart the router in the middle of a game. Anyway with this new D-Link router his NAT type will not come off moderate. Now, I just put it in so I don't know how the performance is yet with us both playing on it because he will not stop complaining about the moderate NAT type, so I've been trying to fix it. Will someone for the love of god please tell me how to resolve this issue so I don't lose my mind.
Thank you.

 

[Sc00T]

Did you check Sony's steps for checking settings on the router? If not I would start there. The link is: How to Change Your NAT Type on PS4 and PS3 | PlayStationing

 

[Sc00T]

Did you check Sony's steps for checking settings on the router? If not I would start there. The link is: How to Change Your NAT Type on PS4 and PS3 | PlayStationing

Sorry its not "Sony's" suggestions but they might help, give them a shot and let us know.