At least it wasn't on Thursday or Friday.
The eShop and all active Nintendo online games are in the process of recovering from an extended outage.
Currently online games are functioning, though users are unable to access the eShop either on the web or on a system. Nintendo of America has acknowledged the errors:
We are aware that players are experiencing errors accessing Nintendo eShop and are working to address the issue. Thank you for your understanding and we hope to share an update when available.— Nintendo of America (@NintendoAmerica) March 17, 2020
A common error message appears to be related to the Domain Name Service (DNS) information for the eShop: depending on the end user's provider of DNS services, a fix can take up to 48 hours to propogate.