Installing Redis
You can speed up your websites by using Redis, its an in memory data store that can be used with WordPress cache plugins to speed up the loading time of your websites.
In the terminal type
sudo apt update
sudo apt install redis-server -y
Install all Redis PHP extensions
sudo apt install php-redis -y
or install them manualy if you need them with
apt install phpX.X-redis
With X.X been the PHP version you want to install (i.e. php7.4-redis for PHP7.4)
Enable Redis to load up when the system is rebooted
sudo systemctl enable redis-server
Edit Redis config file /etc/redis/redis.conf
sudo nano /etc/redis/redis.conf
Find and update the following
maxmemory 256mb
maxmemory-policy allkeys-lru
bind 127.0.0.1::1 to 127.0.0.1
supervised no to spervised systemd
Restart Redis with the new settings
sudo systemctl restart redis-server