Armbian

On an Armbian machine used as a bypass router, both sing-box and WireGuard are running side by side. The router itself resolves internal domain names fine, yet downstream clients that point at it as their DNS server time out every time. The root cause turned out not to be the DNS matching rules, but rather that the traffic sing-box sends to its upstream DNS was choosing the wrong egress interface. ...

After deploying sing-box TUN on Armbian, I encountered a rather counterintuitive issue: IPv6 ping works, but IPv6 HTTPS connections time out after enabling auto_redirect. The eventual finding was that the problem was not with IPv6 public routing or the proxy node, but rather that the Linux loopback interface lo was missing the ::1/128 address. This article documents the diagnostic process and the fix. Environment Linux: Armbian, ARM64, 6.18-series kernel sing-box: 1.14.x Network management: Netplan + NetworkManager Transparent proxy: TUN, auto_route: true, auto_redirect: true IPv6: Automatically configured by the upstream; the interface already has a global IPv6 address and an RA default route To protect privacy, this article omits the actual public IP addresses, MAC addresses, router address, domain names, and custom internal routing table numbers. The ULA addresses and test targets in the following examples are for demonstration purposes. ...