To enable QUIC, there is no configuration change in LSWS. For control panel, QUIC is turned on by default for Apache HTTPS vhosts.

All user need to do is open UDP port 443.

HTTPS with trusted cert, UDP port 443 open at the firewall.

The followings explain the directives could be possibly used but may not necessary at the initial stage.

• Must have QUIC enabled in GUI/conf
• Must use either Chrome or Opera with QUIC enabled
• Must not use self-signed certificates only trusted certificates will work
• Must have UDP Port 443 open
• QUIC will not work with a proxy front end like CloudFlare
• QUIC will only apply to https, not http
• QUIC can be enabled at the server level, listener level or virtual host level

If LSWS is reading your Apache configuration through Plesk you can use the a directive in that file to turn QUIC on or off at the server or vhost level. Add the following directive to the Apache configuration file.

<IfModule LiteSpeed>
  QuicEnable on|off
</IfModule>

When you set QuicEnable at the Apache server level, all vhosts will use that setting as their default. Vhosts level can not rewrite server level.
Please bear in mind that QUIC can only be used for HTTPS vhosts.

Add the following lines into /var/www/vhosts/system/your-domain/conf/vhost_ssl.conf. Create this file if it doesn't exist.

<IfModule LiteSpeed>
  QuicEnable off
</IfModule>