Hi @tao_zhou,
Welcome to the Roon Community. Thanks for writing in to ask us about this issue. From what you described it sounds like there may be an issue with the port forwarding on your Roon server. Can you share a screenshot of your Roon settings → Roon ARC page. Often the error message will make the exact issue clear. You can also try setting up tailscale with Roon. Many users find that easier than port forwarding. This article can walk you through that.