Add bytes dropped counter metric by reason and kind. Fixes tailscale/corp#25918 Signed-off-by: Mike O'Driscoll <mikeo@tailscale.com>
Use envknob to configure the per client send queue depth for the derp server. Fixes tailscale/corp#24978 Signed-off-by: Mike O'Driscoll <mikeo@tailscale.com>