Magento plans to close all traffic from older Magento 1 instances via the Magento Connection Manager (MCM) on March 4th, 2019. This domain (connect.magentocommerce.com)is typically used by older M1 instances for extension support.
Any M1 instance attempting to access the domain will result in a HTTP 404 response.
For M1 instances 1.9.X and 1.14.X, the MCM uses connect20.magentocommerce.com. Access and support will continue as expected for this domain.Access and support will continue as expected for this domain. M1 merchants on 1.8.X and 1.9.X are not affected by this domain deprecation.
If you have any questions, please reply to this post in the comments below. We will respond with updates and further information.