Unable to join public rooms

[matrixbot]

This issue was originally created by @blind-oracle at https://github.com/matrix-org/dendrite/issues/3248.

Background information

• Dendrite version or git SHA: #3244
• SQLite3 or Postgres?: PG
• Running in Docker?: No
• go version: 1.21.3
• Client used (if applicable): Element

dendrite is running behind nginx that does TLS termination and reverse proxy.

    location /.well-known/matrix/server {
        return 200 '{ "m.server": "novg.net:443" }';
    }

    location /.well-known/matrix/client {
        return 200 '{ "m.homeserver": { "base_url": "https://novg.net" } }';
    }

    location /_matrix {
        proxy_pass                 http://127.0.0.1:8088;
        proxy_set_header Host      $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_read_timeout         600;
    }

Description

• What is the problem: Unable to join any public rooms outside my host
• Who is affected:
• How is this bug manifesting:
• When did this first appear:

Steps to reproduce

• Setup dendrite
• Register account
• Try to join some matrix.org or libera.chat rooms
• Observe infinite Joining... spinner

The errors 524/520 look like a Cloudflare timeouts or similar, but doing curl works fine to the given URLs.

In the logs:

Oct 28 18:19:27 novg dendrite[3205549]: time="2023-10-28T16:19:27.855043139Z" level=warning msg="Failed to join room through server" error="r.federation.SendJoin: contents=[] msg=Failed to PUT JSON (hostname \"matrix.org\" path \"/_matrix/federation/v2/send_join/!OGEhHVWSdvArJzumhm:matrix.org/$HohCRwjjZWmrs54SNMven2HXOr-0u2_WdKF0zl4zfJQ\"):  code=524 wrapped=" room_id="!OGEhHVWSdvArJzumhm:matrix.org" server_name=matrix.org
Oct 28 18:19:28 novg dendrite[3205549]: time="2023-10-28T16:19:27.855146010Z" level=error msg="failed to join user \"@blind_oracle:novg.net\" to room \"!OGEhHVWSdvArJzumhm:matrix.org\" through 2 server(s): last error r.federation.SendJoin: contents=[] msg=Failed to PUT JSON (hostname \"matrix.org\" path \"/_matrix/federation/v2/send_join/!OGEhHVWSdvArJzumhm:matrix.org/$HohCRwjjZWmrs54SNMven2HXOr-0u2_WdKF0zl4zfJQ\"):  code=524 wrapped="
Oct 28 18:19:28 novg dendrite[3205549]: time="2023-10-28T16:19:27.855207419Z" level=error msg="Failed to join room" error="contents=[] msg= code=524 wrapped=" room_id="#matrix:matrix.org" servers="[libera.chat]" user_id="@blind_oracle:novg.net"

[matrixbot]

This comment was originally posted by @spaetz at https://github.com/matrix-org/dendrite/issues/3248#issuecomment-1784499497.

I really would not attempt to use the #matrix:matrix.org room as a test. It is a huge broken mess and even synapse seevers often fail to join. Try other, smaller and less broken rooms.