Updated July 2026 · 6 min read
When to enable or disable IPv6
IPv6 ships disabled for a practical reason: most subscription nodes only hand out an IPv4 exit. Switch it on and the system starts preferring v6, which usually walks straight past the proxy.
Why the default is off
On a dual-stack machine the system tries IPv6 first. If your node only offers an IPv4 exit while your local v6 goes out directly, every site with an AAAA record slips past the proxy without asking.
That is the plain argument for leaving it off: all traffic taking the v4 path into the proxy beats half of it going around, because a half-and-half setup makes rule debugging nearly impossible. You never know which half of the traffic a rule even touched.
What it looks like when it goes wrong
The usual sign is a mismatch in location. Some sites still report your own city while others report the node, and which one you get depends only on whether that domain publishes an AAAA record, not on the node you picked.
The second sign is speed that swings. The same site takes two completely different paths on two visits, one through the node and one direct, so latency never settles. It reads like an unstable node when the node is perfectly fine.
There is only one honest check: look up your v4 and v6 exit addresses separately. Both have to show the node. A v6 result matching your home line means traffic is leaking.
When you genuinely need it on
If a device on your LAN listens only on v6, or a company or campus service publishes AAAA records only, leaving v6 off really does mean no access. With a v6-only line from your ISP there is no choice at all.
TUN deserves extra care. Enabling v6 in the client is only half the job, because the TUN stack and DNS have to handle v6 as well. Half a setup usually sends v6 requests into a black hole, which is slower than having it off.
Verify once, straight after
Use a lookup page that shows v4 and v6 exits side by side, or query two single-stack endpoints one after the other. Accept the setting only when both answers give the node address; one out of two is not a working configuration.
If the v6 line shows your home broadband address, v6 is going out directly and the switch belongs back off. Existing connections do not migrate on their own, so drop them on the connections page before you test again.
What is the project?
Clash Verge Rev is a Tauri-based GUI for Mihomo with profile management, system proxy, TUN mode, rule editing and WebDAV backups.