Thanks for the report, @colin_wilson!
May I kindly ask that you please provide a brief description of your current setup using this link as a guide.
Make sure to describe your network configuration/topology, including any networking hardware currently in use, so we can have a clear understanding of how your devices are communicating.
When you reinstalled Windows did you configure your firewall settings for Roon? To find out if it may be a firewall issue you can disable the firewall and try to connect once you’ve done that.
Additionally, have there been any other changes since reinstalling Windows? Any new antivirus? It may be worthwhile to temporarily disable any antivirus active as well and see if it yields any positive changes.
-Dylan