WithRetry : The term 'Install-PowerShell' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again

[2024-12-03T11:02:08.415928+00:00] Installing PowerShell 7
[2024-12-03T11:03:33.963388+00:00] Invoke-RestMethod : Unable to connect to the remote server
[2024-12-03T11:03:33.963547+00:00] At C:\Windows\SystemTemp\d54cbee8-4b8b-46f4-9a40-bbeecf7f79ee\pwpcij52.1jc\main.ps1:127 char:17
[2024-12-03T11:03:33.963553+00:00] + ... $code = Invoke-RestMethod -Uri https://aka.ms/install-powershell. ...
[2024-12-03T11:03:33.963554+00:00] + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[2024-12-03T11:03:33.963559+00:00] + CategoryInfo : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebExc
[2024-12-03T11:03:33.963566+00:00] eption
[2024-12-03T11:03:33.963570+00:00] + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand
[2024-12-03T11:03:33.963572+00:00]
[2024-12-03T11:03:34.048223+00:00] New-Item : Cannot process argument because the value of argument "value" is null. Change the value of argument "value"
[2024-12-03T11:03:34.048450+00:00] to a non-null value.
[2024-12-03T11:03:34.048458+00:00] At C:\Windows\SystemTemp\d54cbee8-4b8b-46f4-9a40-bbeecf7f79ee\pwpcij52.1jc\main.ps1:128 char:17
[2024-12-03T11:03:34.048460+00:00] + ... $null = New-Item -Path function:Install-PowerShell -Value $code
[2024-12-03T11:03:34.048494+00:00] + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[2024-12-03T11:03:34.048500+00:00] + CategoryInfo : InvalidArgument: (Install-PowerShell:String) [New-Item], PSArgumentNullException
[2024-12-03T11:03:34.048506+00:00] + FullyQualifiedErrorId : NewItemValueNotSpecified,Microsoft.PowerShell.Commands.NewItemCommand
[2024-12-03T11:03:34.048512+00:00]
[2024-12-03T11:03:34.128947+00:00] WithRetry : The term 'Install-PowerShell' is not recognized as the name of a cmdlet, function, script file, or
[2024-12-03T11:03:34.129015+00:00] operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try
[2024-12-03T11:03:34.129038+00:00] again.

Note - we have allowed the required network for devbox subnet, but still the customizing failed, please advise.

Start with main.ps1 around lines 127-128, where the script retrieves https://aka.ms/install-powershell and creates Install-PowerShell. Check why Invoke-RestMethod cannot connect and why the resulting null value prevents the function from being created. Done means DevBox customization completes with Install-PowerShell available.