IPv6

WAN6 had obtained an IPv6 address, but when pinging a public IPv6 address on OpenWrt, it immediately returned: ping: sendto: Network unreachable The cause turned out to be an unreachable rule with a mark that was consistent with mwan3. After deleting it, IPv6 connectivity was restored. This case demonstrates that seeing a default route does not mean actual traffic will necessarily use it. This article documents an actual troubleshooting session. The public source address has been replaced with an example address used in the document; device names, rule priorities, and marks should be based on your own device. The uninstallation commands apply to OpenWrt installations that use opkg. ...

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. ...