Ping latency how improve for ps4?

Hope you can help me i have a ping / latency problem with my ps4. For example, when I play COD MW games I have a latency over 50ms to 100ms. Games like GTA or FIFA have never had problems. I don't know what I could do to improve it LAN is not possible because router is on the ground floor and my room in the attic. If I buy a Wi-Fi repeater, would it improve latency?

router: Fritzbox 7560 CN

If you want to keep the ping small, deactivate all other programs if possible,

Deactivating the antivirus program halves the ping, deactivating the firewall does something, e-mail program does everything, everything that wants on the internet except you.

Turning off Wi-Fi does nothing for me. Just do not make the line too fast, this will make it more susceptible to faults and shorten the transmission path