Check-or-Enable-TLS-1.2-with-PowerShell

Pasting Docs Microsoft article extract for future reference (link at the end)

• As of April 2020, the PowerShell Gallery only supports connections using TLS 1.2 or later. For more information, see PowerShell Gallery TLS Support.

  To check your current settings in the Microsoft .NET Framework, run the following command in Windows PowerShell:

  [Net.ServicePointManager]::SecurityProtocol

And to list the available protocols on your local workstation, and on your local Powershell profile you're using (NOTE that you might have different results whether you launched your PowerShell session using elevated prompt):

[enum]::GetNames([System.Net.SecurityProtocolType])

As described in the PowerShell Gallery TLS Support article, to temporarily change the security protocol to TLS 1.2 to install the PowerShellGet or ExchangeOnlineManagement modules, run the following command in Windows PowerShell before you install the module:

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12 

To permanently enable strong cryptography in the Microsoft .NET Framework version 4.x or later, run one of the following commands based on your Windows architecture:

• x64:

  Set-ItemProperty -Path 'HKLM:\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Type DWord -Value '1'

• x86

  Set-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\.NETFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Type DWord -Value '1'

For more information, see SchUseStrongCrypto.

Source: About the Exchange Online PowerShell V2 module

How-To - List all available security protocols from Powershell