Error Message: The underlying connection was closed: An unexpected error occurred on a send. (System.Web.Services)

Error Message: The underlying connection was closed: An unexpected error occurred on a send. (System.Web.Services)

Action: 
My Salesforce connections have suddenly started giving errors. Attached is the error message I am recieving on testing the connections .

Please note the connections were working fine until yesterday and I am getting same issue for both Production and test sandbox.
Error Message: 
The underlying connection was closed: An unexpected error occurred on a send. (System.Web.Services)

Additional information: Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. (System)
Solutions:‚Äč
This error message is most likely caused by an internal firewall and/or change in network policy.
More Information: SOAP API request  - TLS Fingerprint Detection was considered by Security team as a threat and was blocked at the firewall layer ( Requests should be white listed ) .

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