Howdy!
Classic Battle.net has extra rules in place to keep the service safe and help fight against abuse. We cover these rules for the service Here.
In your case, it appears a cloud-based Internet Service Provider was used to connect to the service. This resulted in an action taking place, these actions can last between a few weeks up to 30 days. I would recommend trying to access the service again next week from a private residential Internet Service Provider.
Thank you.