I'm looking for a way to toggle the Gateway server settings on a repository using PowerShell.

I want to be able to set it to and from 'Automatic selection'.
From my initial investigation I've found that the property 'HostId' when running Get-VBRBackupRepository seems to correspond with this GUI setting with '00000000-0000-0000-0000-000000000000' equating to 'Automatic selection'.
Could you suggest how I change this setting alone on existing repositories, to and from 'Automatic selection', presumably using Set-VBRBackupRepository?
Thanks