BBR breaks Web UI on Flint 3 (4.8.4)

Hi everyone,

I’m running a Flint 3 on firmware 4.8.4.

I can successfully enable BBR via SSH (switching from cubic and setting fq as the default qdisc), and the router works fine from a networking perspective.

However, once BBR is enabled:

  • The GL.iNet Web UI becomes inaccessible / unresponsive

  • Routing, internet, and SSH still work normally

As soon as I revert back to:

  • net.ipv4.tcp_congestion_control = cubic

…the Web UI immediately comes back without any other changes.

This is fully reproducible on my setup.

Has anyone else seen this on Flint 3 or 4.8.4?

Is the UI tied to assumptions around cubic, or is there a known incompatibility with BBR + fq on this firmware?

Thank you!