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Unblocking a site

Discovery searches for a bypass strategy that makes a blocked site load and turns it into a set. When no strategy helps, the site can go through a VPN or a proxy instead.

Requirements​

  • b4 is running: Status on the dashboard reads Running.
  • The devices' traffic reaches b4: the dashboard's Activity chart shows connections while they are in use.
  • The address of the site, or of a page on it that does not open.

Setup​

  1. Open Discovery.
  2. Enter the site in Site or URL, for example youtube.com, and press Enter. Sites of one service, such as youtube.com and googlevideo.com, can go in together.
  3. Click Start. A run takes from one to ten minutes.
  4. On a card with a strategy, click Apply as a set.
  5. Choose Create a new set, check the name under Set name, and click Create set.

The new set is enabled at once. The defaults under Options are the usual choice for a first run; the fields are described on the Discovery page.

Checking the result​

  1. Open the site on a device behind the router.
  2. Open the dashboard. The Sets panel lists the new set with the connections it matched in the last hour.
  3. Open Traffic. The site's connections show the new set in the Set column.

When several strategies worked, Use instead under N other strategies worked, or in the Discovery history, tries another one. Its dialog offers to write the strategy into the set that already handles the site, so no second set is needed.

When it does not work​

The card's badge says why no strategy was found:

BadgeCause and fix
address blockedConnections to every address of the site fail, and no bypass strategy can help. The site needs a VPN or a proxy.
intercepted by the gatewayThe first hop in front of b4's host answers the connection itself. When that hop is another router, b4 has to run on it, or b4's host has to be excluded from its redirect. When b4 runs on the main router, only a proxy helps.
does not resolveThe name has no address, as with a misspelled domain.
link answers 400The link answers HTTP 400 even without b4. The link of a page or a file the site serves is needed.
nothing foundA new run with TLS version for the probes set to TLS 1.2, or with a captured ClientHello, sometimes helps. Otherwise a VPN or a proxy is left.

The DPI Detector shows how the ISP blocks a site: by resetting connections, dropping them, forging DNS answers or cutting long transfers. It checks many sites at once, and Fix N with Discovery opens Discovery with the sites still blocked filled in.

When the set exists but the site still does not open:

  • Traffic shows another set in the Set column: that set handles the site, and the new strategy has no effect there. Applying the result with Write the strategy into an existing set and that set puts the strategy where it applies.
  • The browser can reach the site over QUIC (HTTP/3), which Discovery does not test. Block QUIC (force TCP) on the set's UDP tab makes the browser use TCP.
  • The browser can connect over another IP version than the run, for example over IPv6 while the run tested IPv4. A new run with IP version for the probes set to the browser's version tests the site the way the browser reaches it.
  • The site opened before and stopped later: Keeping sets working shows how the watchdog searches for a new strategy on its own.

The full list of checks, from the quickest to the slowest, is under A site does not open.