Step 1: PSN or the game's server may be temporarily unavailable. Please check the status of the game's server via its website. You can check the status of the PSN here.
Step 2: If the servers are active, run the Internet connection test at [Settings] > [Network] > [Test Internet Connection] and make sure you can connect to the network.
Step 3:Update your router to the latest firmware. Turn off other devices that are connected to your network to reduce stress. If this does not work, try again later as the server may be experiencing high volume