Your Lumin D1 is not obsolete because it is Roon Ready and runs the latest RAAT.
If you choose to use Innous as Roon Core, both Innous and Lumin should be connected to your WiFi router or network switch via Ethernet cable.
If you choose to downgrade the current i7 PC Roon Core to hardware that is below Roon minimum recommendations, you may suffer from degraded performance.