I recently changed my Dietpi-based Roon Server from DHCP to a static IP address. The actual IP address has not changed, just the configuration of the network on Dietpi. I did this because I wanted to change it to use OpenDNS rather than my ISP DNS. So DNS changed, everything else remained the same.
Everything is working fine since the change. Except Roon is telling me that ARC will not be able to access the server. But it can access the server. To be clear, ARC is actually working fine.