I am not sure, whatever was the last released. I always keep it up to date. I have rebooted the NAS, I have uninstalled the software and reinstalled it. Same result
I figured out the issue, it was the VPN that is installed on the NAS. It has been running for a year without issue, I disconnected from it and Roon fired right up. I connected back to it, and Roon disconnected. So not sure what changed with the latest build but something did.