I am using DDNS, domain name : hjianhao.f3322.net, mapped IP is 113.xx.xxx.59, I can access my NAS, router, raspberry pi SSH correctly. I used link you give, this site say my computer IP is 188.8.131.52, and I can’t specified IP, so I can’t test my domain’s port.
I’ve read your posts a few times now. A few things came to mind: see below. Also, I don’t quite understand your setup. It looks like you have placed a router behind a router (and thus NAT behind NAT) where the function of second router is fulfilled by a Raspberry. Such a setup with two routers is sensitive to the kind of problem you describe (see posts about it on this forum).
Other things that comes to my mind when I read your posts (maybe they help you finding the problem and a solution or giving you new ideas):
I am not sure but I think that the two subnets you have behind each other are using the same IP-range (192.168.1.0-192.168.1.254). Although this is possible from a theoretical point of view, it does not increase comprehensibility. My advice would be to use different IP ranges for the two subnets.
In your post I see different IP addresses for your internet connection. I see for example: 153.ddd.ddd.eee, 184.108.40.206, 220.127.116.11. It could be that this is a problem for Roon ARC. Perhaps that during the Roon ARC test Roon Core is sending an message to the central Roon Server on one internet IP address while the confirmation is expected on another internet IP address. Or something like that.
Is it possible to do a test with the Raspberry temporarily removed from your setup (with the portforwarding from internet via the first router) directly to your NAS IP address? If this is working than you know the problem has something to do with the settings in the Raspberry.
Did you do a test with the NAS firewall and/or the Raspberry firewall disabled?
You have my sincerest apologies for the delayed response here, we’ve been dealing with a higher-than-usual volume following our release and we’re working as quickly as we can to get back to everyone.
Following up on this thread, @Alfred_van_Hoorn has made some excellent points, and has absolutely asked the proper next questions. Did you end up getting Arc sorted out, or are you still running into issues?