How To enable BBR On Debian

echo "net.core.default_qdisc=fq" >> /etc/sysctl.conf
echo "net.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf
sysctl -p

If BBR is enabled in your system, you can see the words like bbr.

sysctl net.ipv4.tcp_available_congestion_control
lsmod | grep bbr