This login failure is due to Salesforce disabling TLS 1.0 encryption protocol. In Sandbox orgs, TLS 1.0 cannot be enabled. However, in Production orgs, TLS 1.0 can be enabled by deactivating the setting "Require TLS 1.1 or higher for HTTPS connections” in Critical Update Console (CRUC). This setting will be available till 3rd of March, 2017. To know all details about this change, refer to Salesforce Knowledge Article 000221207 (https://help.salesforce.com/apex/HTViewSolution?id=000221207).