Problem: Call of Duty World War 2 (WWII) prompt error ?service is not available at this time? with error code 4220 and unable to connect to online multiplayer mode.
Solution 1: Power Cycling ConsoleSolution 2: Login to WWII Nazi Zombies before connect to normal multiplayerSolution 3: Check Internet connection settings from consoleSolution 4: Set the right NAT typeReference
Solution 1: Power Cycling Console
Completely shut down your console, router, modem and plug out main power supply for around 5 minutes in order to erase any bad configurations and refresh their state.
Solution 2: Login to WWII Nazi Zombies before connect to normal multiplayer
Step 1: Launch Call of Duty WWII on your console, connecting to Xbox Live, then click the option Nazi Zombies.
Step 2: Click on Multiplayer to navigate back to the main menu.
Solution 3: Check Internet connection settings from console
Step 1: Open console settings > Network > Test Internet Connection.
Step 2: Now console will start to check the internet connection details and confirm the connection is established.
Step 3: Now open Call of Duty WWII again and try connecting to Xbox Live.
Solution 4: Set the right NAT type
For Xbox, it is recommended that NAT type set to Open. Go to Settings > All Settings > Network > Test NAT type and make sure it is set to Open.
For PS4 the NAT type should be Type 1. Go to Settings > Network > Connection Status > Set NAT type to Type 1.