Pradeep,
You’re getting a 404, not a timeout, so I’d really double check. 
Maybe your DevOps team should join this community!
With regards to Microsoft IP addresses, that’s probably a question best suited for Microsoft. There seem to be some details here with regards to hosted azure devops agents: https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops#agent-ip-ranges
Colin