Add-AdfsDeviceRegistrationUpnSuffix is accessible with the help of adfs module. To install adfs on your system please refer to this adfs.
Synopsis
Adds a custom UPN suffix.
Description
The Add-AdfsDeviceRegistrationUpnSuffix cmdlet adds a custom user principal name (UPN) suffix that you can use when you register a device with Active Directory Federation Services (AD FS).
In many environments, additional UPN suffixes for users are added after an Active Directory Federation Services (AD FS) deployment is complete. Run this cmdlet to support device registration for users of the new UPN suffix. The cmdlet configures a Secure Sockets Layer (SSL) binding that corresponds to the UPN suffix. The UPN suffix must have a corresponding registration name in the AD FS SSL certificate, for example enterpriseregistration.upn suffix. You can use a wild-card SSL certificate that covers all possible registration names.
Parameters
-Confirm <>
Required? false
Position? Named
Default value
Accept pipeline input? false
Accept wildcard characters?
-UpnSuffix <string>
Required? true
Position? 0
Default value
Accept pipeline input? true (ByValue)
Accept wildcard characters?
-WhatIf <>
Required? false
Position? Named
Default value
Accept pipeline input? false
Accept wildcard characters?
Syntax
Add-AdfsDeviceRegistrationUpnSuffix [-UpnSuffix] <String> [-WhatIf] [-Confirm] [<CommonParameters>]
You can check the Version, CommandType and Source of this cmdlet by giving below command.
Get-Command Add-AdfsDeviceRegistrationUpnSuffix