I had SXOS 2.0.1 with 6.1.0 for like 2 weeks. Only played xci and nsp backups, airplane mode all the time. Decided to go back to OFW 2 days ago. Restored a 6.1.0 NAND backup done through SXOS RCM Menu BEFORE installing any CFW (so it was definitely clean). Online worked fine for this 2 last days. This morning got a 6.2.0 update request and now I get "This nintendo account cannot be used at this time, this user can't use online features" when trying to acces e-shop or add new nintendo account. Later inspection on error history found code "2154-2005" that doesn't appear in nintendo's error logs. Technical support for nintendo on the phone said to try connecting and disconnecting wifi, deleting it and adding it again, try other internet connections etc. None worked. I'm now being told to send it in to check.
Any solutions, further info about this error and why it happened. I'm pretty shure I did all the possible to avoid any "known" ban (No internet on CFW, OFW Nand backup and restore)