The reference to a router external ip address of 100.aaa.bbb.ccc combined with MultipleNatFound is highly indicative of the use of CG-NAT by your ISP.
This being the case, Port forwarding will not work unless your ISP can offer you a true public ip address provision without the use of CG-NAT - often a static ip address - and often at additional cost
Without a public ip address the only solution that will work is to use Tailscale as suggested (or an equivalent VPN solution - but Tailscale is the only supported one).
The only thing that I can add is that, if you use a bios boot.RoonOS device for your Roon server (Nucleus, Nucleus Plus, some ROCK installs) such that the RoonOS version will not update beyond build 259, then you will not be able to run Tailscale directly on your Roon Server. Instead you will have to run it as a subnet router on a separate, always on computer - maybe something like a Raspberry Pi.
The description of how to do this can be found at:
More information on what a Tailscale subnet router is can be found at:
Also, in this situation where you can’t run Tailscale directly on your Roon Server, it may be worth looking at your router (the Nexxt One) to see if it offers the possibility of setting up Wireguard on the router itself. If Wireguard is supported on the router, then, whilst not officially supported, Wireguard will work in an almost identical way to the Tailscale subnet router - but may be easier to configure.
Just to reiterate for clarity: your internet service provider has network implementation that will block Roon and ARC from automatically connecting.
An alternative would be to install Tailscale, but older generation Nucleus models won’t have Tailscale pre-installed.
I recommend instead that you reach out to your internet service provider directly and request if they have a dedicated external IP address available for your account tier.
Most internet service providers will offer a dedicated external IP address, sometimes for a small one-time or monthly fee.
Please let us know if this helps. We’ll await your response in the meantime. Thank you!
We wanted to equip you for success with port forwarding and Tailscale, because this thread will soon automatically close without a response.
First off, the easiest solution to your issue would be to contact your internet service provider and request a dedicated external IPv4 address. If you provide the name of your ISP, we can let you know if other users on this forum have found success with this option.
Otherwise, you’ll need to set up Tailscale.
Starting with the basics, Tailscale is an alternative to port forwarding with Roon/ARC. This means that you can ignore the port forwarding diagnostic test in Roon Settings → ARC entirely if you’re choosing to install Tailscale, since it will be a completely separate network pathway.
Tailscale provides robust NAT traversal for RoonServer and ARC. In simple terms, this means that it will help RoonServer connect to ARC regardless of the network settings or infrastructure in between.
However, since your Nucleus doesn’t have Tailscale pre-installed, you’ll need to use another computer on your network as a “subnet router.” This computer will relay RoonServer’s connection to the internet through Tailscale.
This requires some delicate configuration, but once configured, you won’t need to touch it. Here is a guide from Tailscale:
Hopefully, this helps. We’ll watch for a response, but without any action from the OP, this thread will soon close. Thank you!
