Nintendo has already started winding down online play on the 3DS and Wii U.
Pretendo has reported that from late December 2023, new users on both consoles have been unable to play games online. This has occurred slightly ahead of April 2024, which is the date that Nintendo previously announced that online play would end.
According to the post, if new players try and go online they will be met with the message 'Error code 106-0303' on Wii U and 'Error Code 006-0303' on 3DS.
This sadly marks the beginning of the end for online play on the Wii U and 3DS. So if you're an existing user, you might want to dust off your console and play some Super Smash Bros., Super Mario Kart, or many of the other great titles online ahead of April 2024.
Thanks, Nintendo Life.