Significantly increase TCP throughput (and thus network speed) of your Linux server. When I tried it on a VPS I own, the wget average went from 394KB/s to 1.37MB/s!

enable-tcp-bbr.sh

#!/usr/bin/env bash

# This is a crazy feature of the Linux kernel that will DRAMATICALLY increase
# the TCP throughput (and thus network speed) of your Linux server.
# When I tried it on a VPS I own, the wget average went from 394KB/s to 1.37MB/s!

# Further reading: https://medium.com/google-cloud/tcp-bbr-magic-dust-for-network-performance-57a5f1ccf437

# check if kernel supports TCP BBR
if ! grep 'CONFIG_TCP_CONG_BBR' /boot/config-"$(uname -r)" | grep -q 'CONFIG_TCP_CONG_BBR'; then
    echo ""
    echo "Your kernel does not support TCP BBR."
    echo "Make sure you have the latest kernel installed, and is not using OpenVZ virtualization."
    echo ""
    exit 0
fi

# if kernel supports TCP BBR, then check if it has been enabled
echo ""
sysctl net.core.default_qdisc
sysctl net.ipv4.tcp_congestion_control
echo ""

# if already enabled, notify user, take no further action, exit script
if sysctl net.core.default_qdisc | grep -q 'fq' && sysctl net.ipv4.tcp_congestion_control | grep -q 'bbr'; then
    echo "TCP BBR Congestion Control is already ENABLED in your system!"
    echo "No further action necessary."
    echo ""
    exit 0
fi

# pause and advise the user to speedtest before continuing
echo ""
echo "Congratulations! Your kernel DOES support TCP BBR!"
echo "You might want to exit the script now and test the download speed to compare afterwards."
echo ""
echo " Press Ctrl+C to exit,"
read -p " press [Enter] to continue..."
echo ""

# edit TCP BBR settings
sudo touch /etc/sysctl.d/10-custom-kernel-bbr.conf
echo "net.core.default_qdisc=fq" | sudo tee -a /etc/sysctl.d/10-custom-kernel-bbr.conf
echo "net.ipv4.tcp_congestion_control=bbr" | sudo tee -a /etc/sysctl.d/10-custom-kernel-bbr.conf

# apply the changes
sudo sysctl --system

# verify
echo ""
sysctl net.core.default_qdisc
sysctl net.ipv4.tcp_congestion_control
echo ""

# exit message
echo ""
echo "All the settings have been applied!"
echo "You might want to reboot the server and test the download speed again."
echo ""