Microsoft is rolling out a change regarding TLS 1.2 for security reasons.
To resolve the issue, please check if TLS 1.2 is properly configured/enabled on the machine running the Cloud Connector. Various steps may be required for activation. Please refer to the following links:
https://www.layer2solutions.com/support/cloud-connector-faqs/how-to-enable-tls-1.2-on-a-cloud-connector-host-machine
https://docs.microsoft.com/en-us/sharepoint/troubleshoot/administration/authentication-errors-tls12-support
The underlying connection was closed: An unexpected error occurred on a send.
