Need to test your PHP binary.
Do not give up yet.
What you observed is normal. Once you try to access the admin interface, the web server will bind (use) port 5158 and start PHP, so when you do netstat again, it shows port 5158 is in use, if you kill all the running PHP processes, that port will be released.
For some reason the Fast CGI interface on PHP side is broken and no request can be completed, when that happens, web server will try to restart PHP engine and try again, but the port is still used by left over PHP processes. That is the reason why you saw that warning.
First we need to make sure your PHP binary is ok. Try it form command line first, see if there is any error messages, run "php -i" to make sure Fast CGI interface is enabled (configured with --enable-fastcgi).
If configuration file path for PHP is set to /usr/local/lib (it is the default value, my instrution change it to ../conf), make sure the notice logging is not enabled, it will break the fast CGI interface.
Then turn on server's debug logging by editing file "lsws/conf/httpd_config.xml", change "debugLevel" to 10. stop server, kill all PHP processes, start server again and access the PHP test page (not the admin interface).
If you still get 503, compress the error log and send it to
bugs@litespeedtech.com.
We will try our best to help you.
Thank you for your patience.
Mistwang