You are unable to sign in to your Nintendo Account on Nintendo Switch and receive the error code 2124-5200.
This error indicates that there is likely a temporary service outage related to Nintendo Accounts.
What to Do:
Wait a while and try again later.
Situation Not Resolved:
If the issue persists, visit the Network Maintenance page and check for any posted service maintenance or outages.
If you would like further assistance with the Nintendo Switch console, please contact Nintendo Customer Service.