· I am a new Roon user, and installed Roon Core on NAS Synology. I use 1 ISP Modem F@ST3896LG-TN, tried UPnP: did not work Port forwarding: TCP connection, internal and external port 55002: other working.
· I have VPN, but is not activated for NAS. NAS is connected through a D-link switch (but I have no idea how to work with that). On NAS Plex server installed: remote service working
Looking at the error log you provided (Status Code 504 / ETIMEDOUT), it looks like the Roon cloud is trying to reach your Core, but the connection is being dropped before it hits your NAS. Here is a checklist to get your ARC up and running:
1. Check the Synology Internal Firewall
This is the most common "silent killer" for Roon on NAS. Even if the router is configured correctly, the NAS might be blocking the incoming request.
Go to Control Panel > Security > Firewall.
Either temporarily disable it to test the connection or add an Allow Rule for TCP Port 55002.
2. Verify "Double NAT" or "Carrier-Grade NAT" (CGNAT)
The error router_external_ip: null suggests Roon can't see a clear path to the internet.
Check your Sagemcom F@ST3896LG status page. Look for the WAN IP address.
The Test: If that WAN IP starts with 10.x.x.x, 192.168.x.x, or 100.x.x.x, your ISP is using CGNAT. If this is the case, standard port forwarding won't work, and you will need to ask your ISP for a "Public/Static IP" or use a workaround like Tailscale.
3. Docker Configuration (If applicable)
Are you running Roon via Container Manager (Docker) on your Synology?
If yes, ensure the container is set to "Use the same network as Docker Host" (Host Mode).
If it’s set to "Bridge Mode," the port forwarding will fail unless you also map the port within the Docker settings.
4. Port Forwarding Specifics
Since UPnP failed, stick with the manual rule you created, but double-check these two things:
Static IP: Ensure your Synology NAS has a Reserved/Static IP in your router settings so the port forward doesn't "break" if the NAS reboots and gets a new internal address.
TCP Protocol: Ensure the rule is specifically set to TCP (Roon ARC doesn't require UDP for the handshake).
5. The "D-Link Switch" Factor
If it’s a simple "unmanaged" switch, it shouldn't be an issue. However, if it’s a Managed Switch, it might have its own security settings or VLANs. If possible, try connecting the NAS directly to the Sagemcom modem for 5 minutes just to rule the switch out as a culprit.
Quick Next Step: Try disabling the Synology Firewall first - if ARC suddenly says “Ready,” you just need to add that specific port exception.
Thanks for replying. As I am still in the trail period, I want to be sure that Roon ARC works before considering buying the software.
ARC is still not working. Setup is following:
NAS Synology DS918+ with Roon Core installed. Access to my own songs is working, as is Tidal and Qobuz. RAM usage 80-90% due to 4Gb RAM → I am considering installing additional 4 Gb RAM
Clients are: HomePod (1st gen - is not recognised with Roon icon unlike the HomePod mini), HomePod mini, Marantz AVR, iPhone, iPad
As for your steps I experience following:
CGNAT: WAN IP and check whatsmyip = IP address is the same → = okay?
DSM Firewall: I disabled the Firewall, but I am using Docker and setting is “host” → okay
Port forwarding: UPnP not working, disabled that. I tried manual port forwarding; setting local IP address 192.168.x.x external and internal port 55002 to 55002, TCP → enabled but Roon ARC can not connect to the server In the Roon ARC settings (client), listening port ‘Roon Server IP” is same as port in port forwarding, as is the port itself (55002) NAS has a static IP (same as local IP) Error:
hi Benjamin, trying to figure out what can be the issue here, but my trial expires soon. Is there a possibility to have a bit longer the trial, since I am struggling to fix my ARC connection?
I completely understand wanting to ensure every feature works perfectly before committing to a subscription, and we definitely want you to have enough time to test Roon ARC! I will pass your request along to our accounts team to see about getting your trial extended while we troubleshoot this.
In the meantime, let’s break down exactly what is happening with your connection. There are two key factors in your setup that are blocking ARC from functioning normally.
To be completely transparent, running Roon Server inside a Docker container is not officially supported. While setting the container to “host” networking seems like it should bypass Docker’s internal routing, Synology’s underlying OS architecture still applies virtualized network and firewall rules to Docker containers.
Since you have already confirmed that your WAN IP matches your public IP (meaning no CGNAT) and your manual port forwarding rules are correct, the Docker environment itself is almost certainly intercepting or blocking the incoming ARC handshake.
You mentioned that Tailscale didn’t work either, but there is a very important detail regarding how Roon reports VPN connections.
When you use a VPN like Tailscale, the Settings > Roon ARC tab inside your Roon Server will always display a red error message (like the 504 error you shared).
This is because Roon’s internal diagnostic tool only checks for traditional UPnP or Port Forwarding over the open internet from our servers. It cannot “see” the secure Tailscale tunnel. If you have Tailscale actively running on both your Synology and your iPhone, you must completely ignore the error in Roon’s settings.
To get ARC up and running before your trial ends, here is what we recommend:
Test Tailscale directly: Make sure Tailscale is active and connected on both the NAS and your phone. Disconnect your phone from your home Wi-Fi (use cellular data), ignore the error in the Roon settings on your computer, and simply launch the ARC app on your phone. It should connect right through the tunnel.
Move away from Docker: If you want to use standard port forwarding instead of Tailscale, you will need to install the native Roon Server package for Synology (maintained by Christopher Rieke) rather than using Docker. This will eliminate the virtualized network layer that is currently blocking the port.
Would you like to give the Tailscale test a try first, or would you prefer to reinstall Roon as the package from the store ?
