The Diablo II servers will automatically restrict connections when a game client is performing unauthorized behaviors.
Connection restrictions in Diablo II can be applied for behaviors such as:
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Connecting to Battle.net using a business network, cloud hosting service, VPN, or Proxy
If you find that your connection has been temporarily restricted, please remain offline for at least 48 hours. If after 48 hours you are still restricted, reinstall your game client or acquire a new IP address.