Hi @Marcin_Rosiak,
Please accept our apologies for the long wait time in responding to your thread. Rest assured we’re be more responsible moving forward now that we’ve caught up on the uptick in inquiries after the release of Roon 2.0.
Our goal is to get ARC working for every user who isn’t encountering a truly prohibitive issue with their ISP. While there are providers with whom ARC simply won’t work with port forwarding and unofficial workarounds like this one will be required, we can resolve the issue without contacting the ISP in many cases.
Here are instructions you can use to set up a port forwarding rule manually on the D-Link router you are using: Simple D-Link DIR-825ACG1 Router Port Forwarding Instructions
However, the message you’ve shared in the diagnostics, multipleNATfound, does suggest that there’s an additional modem/router in your setup. Can you please confirm the brand and make of modem/router you’re using? If the unit doesn’t offer Bridge mode or equivalent, we can still likely configure the second router as a safe “Access Point” to enable port forwarding securely.
Again, I’m very sorry for the long wait. I’ll be watching closely for your response, and hopefully we can resolve your connectivity issues promptly.