Just a fellow Roon user here. It would be really helpful if you stuck with the original thread where @BlackJack was kindly assisting you.
What’s more, please describe your setup as described in this post, so you get some assistance from Roon Support or the community. The other thread implies that your DAC is connected to the Core, but you also mention a Raspberry Pi. In addition, you should connect your Core and Pi to the network using Ethernet.