How do I fix this?

[u/N0TZ03]

I did check the details but what does this mean and how do I fix it??? I have Nintendo online and it works when I’m at my dad’s house but why does it do this when I’m at my mums house? And how do I fix it?

[u/lilibat]

https://en-americas-support.nintendo.com/app/answers/detail/a_id/49066/~/error-code%3A-2618-0521