I wrote about cPanel proxy, but there is also problem with proxy to DirectAdmin backend. After setup the proxy works, but the problem is after succesful login to DirectAdmin. The site is being redirected to the port 2222. When we remove the port from the URL bar (after login) then we can access the DirectAdmin by port 80.
We wrote about this problem to DirectAdmin support, but they said that LiteSpeed propably send anouther headers then Apache, because the problem doesn't occur at servers using Apache.