17 days ago - AndrewT - Direct link
Are you playing with other Epic users, or are they on Steam or elsewhere?  
16 days ago - AndrewT - Direct link
The point being, Steam users will have to pick the Nakama option when they start their game to play with you, otherwise they can only play with other Steam users via the Steam MP servers.

If however you get this issue with exclusively Epic players that cannot be the problem. In fact it sounds like the MP issue that CK3 has had for some time!
We have three possible workarounds that may solve it:

Disable IPv6
- Close CK3
- Go to Control Panel > View Network status and tasks > Change adapter settings (left side)
- Find your Hamachi Connection and Disable it
- Find your Internet connection adapter (for me, it was WiFi)
- Right click your internet adapter and select properties
- Scroll down to find "Internet Protocol Version 6 (TCP/IPv6) and uncheck the box
- Select Ok
- Start up CK3 and should work.

Disable all other network adapters

  1. Go to Windows Control panel.
  2. Click on Network & Internet.
  3. Click on View Network Status.
    Quick Tip: You can also quickly access these settings by right-clicking the network icon in the taskbar and selecting the Network & Internet settings option.
  4. Click on Change adapter options.
  5. Right-click all network adapters that are not connected to the internet and select the Disable option.

Use a VPN

- Obtain a VPN

- Set the country to the US (why this works is also an enigma ><)

- Start the game

- Sign in and see if it "sticks"  
15 days ago - AndrewT - Direct link
Great! Can you say which one?