Go to Settings>Network>Set Up Internet Connection.  2. Then run all the settings as they are in automatic  3. However, switch to Manual for the MTU settings, 4. Then keep lowering the MTU value on your PS4 by manually a lower MTU value each time.input the value you want. 5. Keep testing your internet connection with each progressively lower MTU value until your connection test screen displays that “packets are no longer able to be fragmented” 6. Then add 28 with it. That should be the optimal MTU for your Ps4. That’s how you set up the optimal MTU in Ps4.