New router and now Roon ARC cannot access my Roon Core

[Menzies]

Unfortunately I’m now sure your ISP is a CGNAT provider.

The below thread may be of interest. You will need to contact your ISP and discuss your options I’m affraid.

Unable to configure Arc

Yes. ummm “no”, but that’s my opinion. This is the real reason and this is why more and more ISPs will start using this until IPv6 is more widely deployed and in use. VPNs yes. Port Forwarding absolutely no. Not without the ISP putting rules into their CGNAT infrastructure to forward inwards to you. If you want to avoid the $10 then look into some of the great write-ups others have done here for getting VPNs working. I like the Tailscale solution personally although I don’t use it.