Migrate gateway to new server

Hi,

I have read up on this topic at length but am drawing a blank as to how it should actually work.

I have an existing MSSQL 2012 instance on a VM in Azure which (via On-Prem gateway) provides data to PowerBI online where my data team have many reports.

I would like to migrate the gateway to a new VM running MSSQL 2017. I have loaded the same SSAS cube data on the new server as the old one. Both VMs are joined to Azure AD via Domain Services.

I need to make sure that all of the reports/datasets/workspaces in PowerBI Online stay working.

The way I see it I have 2 options:

- Start a Gateway config on the new server and choose "Migrate..."

- Start a new Gateway on the new server and cluster it to the existing, then remove the old server

When I tried the former all of the reports in PowerBI Online stopped working. When I try clustering, I get the error "AdomdException encountered while connecting to the target data source", referring to the new server. Also I don't know how to stop the old server being set as "isAnchorGateway".

What is the best way for me to proceed?

Thanks

Andrew