Well, it’s been running alongside Plex for more than a year now without any issues. I’m also seeing others say the same like this post here. Also, I have the DLNA server in Plex disabled as I don’t use it so it shouldn’t be listening at port 1900 at all. When I check though, I have the minidlnad service conflicting with Roon:
root@nuc:~# ss -ulpn | grep 1900
UNCONN 0 0 0.0.0.0:1900 0.0.0.0:* users:(("RoonAppliance",pid=272463,fd=639))
UNCONN 0 0 0.0.0.0:1900 0.0.0.0:* users:(("RoonAppliance",pid=272463,fd=636))
UNCONN 0 0 0.0.0.0:1900 0.0.0.0:* users:(("RoonAppliance",pid=272463,fd=635))
UNCONN 0 0 239.255.255.250:1900 0.0.0.0:* users:(("RoonAppliance",pid=272463,fd=616))
UNCONN 0 0 239.255.255.250:1900 0.0.0.0:* users:(("minidlnad",pid=1749,fd=6))