You are unable to connect online and receive an error between 2124-0200 and 2124-0269.
You may receive this error code if you are attempting to use a game's online features, but for some reason you are currently not logged in to your Nintendo Account.
Complete These Steps:
Press the HOME Button to return the HOME Menu and select your user icon from the top-left corner.
When prompted, sign in to your Nintendo Account.
Once you confirmed you are signed in to your Nintendo account, press the HOME Button again to return to your game.