Nw 31281-5 error code for ps4?

When I play a game online at ps4 eg. Fifa19 the internet connection goes every 30 min. Way (error code nw 31281-5) after 10 seconds the internet connection comes back but the game is ended and I have to start again. I have an internet connection from unitymedia 400mbit (connected with a lan cable). How can I solve this problem? (I have already made dns settings, it only works for 2 minutes. Then the internet is gone again without an error code)

Your console is not assigned a local IP address by the main router. This can be changed / corrected by changing the network settings of your PS4.

Thanks for the answer, how can I do the network setting?

That should be the solution https://portforward.com/networking/static-ip-ps4/