When you try to install PowerShell modules from the online PSGallery, you may see the following error:
Install-Module SqlServer WARNING: Unable to resolve package source 'https://www.powershellgallery.com/api/v2'. PackageManagement\Find-Package : No match was found for the specified search criteria and module name 'sqlserver. Try Get-PSRepository to see all available registered module repositories. NoMatchFoundForCriteria,Microsoft.PowerShell.PackageManagement.Cmdlets.FindPackage