Nintendo will once again be dealing with some online maintenance tasks later this month. As on January 18 (Pacific Time), Nintendo noted “all network services will be unavailable” while it performs maintenance tasks on the Nintendo eShop for 3DS, Wii U, and Switch.
Relative short maintenance window
The maintenance deals with the use of Prepaid Funds Cards and Download Codes. It should take from Monday, January 18, 2021 12:00 PM – Monday, January 18, 2021 4:00 PM Pacific Time
If you have any plans to access the Nintendo eShop during this time period, you might want to plan around this disruption of services.