Troubleshooting

Troubleshooting

🌐 English · Русский · 中文

What common situations mean and what to do. When reporting a problem, a screenshot of the Logs around connect/import is worth more than any description.

A node "pings" but pages don't load

The latency test runs from the core directly to a test URL, bypassing the tunnel — so a green ping only proves the core can reach the server, not that TUN-routed traffic works. Usual causes:

• DNS is failing. If lookups don't resolve, you'll see dns resolve failed: couldn't find ip in Logs — for proxy servers and direct sites. Try switching DNS to reliable resolvers (e.g. 1.1.1.1 / 8.8.8.8); some subscriptions ship slow or unreachable DNS.
• Broken IPv6. Errors like dial tcp [2600:…]: The requested address is not valid in its context mean your machine has no working IPv6 route but the config returns IPv6 addresses. Set the config's top-level ipv6: false (SlothClash's default already follows this).
• Rule lists pulled through a dead proxy. If a subscription fetches its rule providers proxy: through a node that's down, Rule mode has nothing to match on. Pick a working node or check with your provider.
• MTU / UDP. QUIC-based protocols (Hysteria2, TUIC) can ping yet stall real traffic if the TUN MTU is too high. Try Settings → TUN → MTU = 1408, or test in System-proxy mode to confirm it's the TUN path.

Import succeeds, but nothing works after connecting

Almost always the rule-provider-through-a-dead-node case above, or a DNS problem. Open Logs and look for initial rule provider … error or dial … i/o timeout — the address in the dial line tells you which node couldn't be reached. Pick a different node and reconnect.

TUN won't come up / connects then drops

• SlothClash verifies the TUN adapter after bring-up and will restart the core once if it didn't come up cleanly; give it a few seconds.
• Make sure the helper service is installed and current — if the app shows an update-service banner, follow it. A version mismatch can block TUN.
• On Windows, third-party network filters can interfere. On macOS, a utun … Operation not permitted usually means another network filter (e.g. Cisco AnyConnect) is blocking the tunnel — quit it and retry.

The "update helper service" banner

The desktop app and the privileged service must match. The banner appears when they drift (usually after an app update). Follow it to update the service; TUN stays reliable once they're in sync.

Windows: Visual C++ runtime prompt during install

SlothClash needs the Microsoft Visual C++ runtime. If the installer prompts for it, allow the install — it's a one-time system dependency.

Reading Logs

Logs shows the core's own messages. Useful lines:

Line	Meaning
dns resolve failed: couldn't find ip	DNS couldn't resolve — see the DNS section above
dial tcp [2600:…]: … not valid in its context	Broken IPv6 — disable IPv6 in the config
[TCP] dial <group> … i/o timeout	The node <ip> is unreachable
initial rule provider <name> error	A rule list failed to download (often through a dead node)

Related

• Settings — TUN stack, MTU, DNS
• Profiles & Nodes — switching nodes