FROM: https://stackoverflow.com/questions/72031733/the-online-service-is-not-available-issue-in-visual-studio-professional-2013-w



Try this; it worked for me. Just add two DWORD values to the Windows Registry. Site go.microsoft.com now supports only TLS1.2 protocol.

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001