Can't get into Realms on Minecraft: Java Edition? Due to GDPR (http://minecraft.net/privacy/gdpr/ ) users under the age of 16 need parental consent to play on Realms. To set up parental consent on an account, visit http://minecraft.net/update-account .
While this is most likely a temporary issue, please try logging out and back into your Microsoft (Xbox Live) Account in the game settings. For support from Nintendo, you can use this link here https://en-americas-support.nintendo.com/app/contact I hope this helps! ^SA