From one of your posting you indicate it was a proxied when on Windows. Was old site setup with load balancing? Networking comes before application, so is there something network wise that is in front of the CentOS server you now have that expects the CentOS server to be proxied?
If you don't need the proxy line in config.php, rather than setting it to 'false' just comment out the line with // in front of that line. No need to restart apache, just access the site.
What is in your httpd.conf file? Are there settings for 'proxy'?
Web server logs /var/log/httpd/ especially the error_log ... shows/says nothing?
From command line, cd /var/www/html/ (where your moodle code probably resides.
Then again cd admin/cli/
Run php cfg.php |grep proxy
That script reads the DB for settings .... all of them ....
On a server that is not proxied, this is what should show:
[root@sos cli]# php cfg.php |grep proxy
proxyhost
proxyport 0
proxytype HTTP
proxyuser
proxypassword
proxybypass localhost, 127.0.0.1
There should also be no active proxy settings in /etc/httpd/conf/httpd.conf file.
fgrep 'proxy' /etc/httpd/conf/httpd.conf
should show nothing.
Purge the moodle cache manually.
cd /path/to/moodledata/
manually remove contents of cache, localcache directories. Those should rebuild as site is used.
Turn on debugging via config.php file:
// @error_reporting(E_ALL | E_STRICT); // NOT FOR PRODUCTION SERVERS!
// @ini_set('display_errors', '1'); // NOT FOR PRODUCTION SERVERS!
// $CFG->debug = (E_ALL | E_STRICT); // === DEBUG_DEVELOPER - NOT FOR PRODUCT$
// $CFG->debugdisplay = 1; // NOT FOR PRODUCTION SERVERS!
'spirit of sharing', Ken
