No luck getting this working at all yet.
Port forwarding set up on both, static IP for the Roon core.
Modem will not work in bridge mode.
Plex works fine, Roon does not. Tempted to drop the subscription at this point!
I’ve posted many times on this forum about Aussie Broadband, as @Rugby posted, they use CG-NAT.
There are two ways to get ARC working whilst with ABB as your provider, pay extra for a static IP or call up their support and ask to opt out of CG-NAT, they will want a valid reason, tell them you have a service that requires Port Forwarding.
I’ve been through this process with Aussie Broadband so I know that it works.
My modem at the time was a D-Link Python DSL-2888A set up in bridge mode with an ASUS RT-AC88U handling the WAN and LAN routing.
@CrystalGipsy, your question is by no means unwarranted. For a quick answer: Plex uses their own servers to do the heavy-lifting in circumstances where users must circumvent CG-NAT. There are several reasons why Roon has chosen a different implementation so far with the release of ARC. I recommend posting in #roon if you’d like to invite some clarification on this matter.