1. Check the system version

$ lsb_release -a

Distributor ID: Debian
Description: Debian GNU/Linux 10 (buster)
Release: 10
Codename: buster

2. Modify system variables

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

3. Save effective sysctl -p
4. Check whether the kernel has BBR turned on

sysctl net.ipv4.tcp_available_congestion_control

The following is displayed:

$ sudo sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic bbr

5. Check whether BBR is activated

lsmod | grep bbr

The startup is successful when the following is displayed:

$ lsmod |grep bbr
tcp_bbr 20480 7