Fatal error: Uncaught Error: Call to undefined function shell_exec() in /home/p1660/domains/captiveportal-billing-ccc02bd4-1660.app.omni-coder.com/public_html/functions.php:25 Stack trace: #0 /home/p1660/domains/captiveportal-billing-ccc02bd4-1660.app.omni-coder.com/public_html/index.php(15): getUserMacAddress() #1 {main} thrown in /home/p1660/domains/captiveportal-billing-ccc02bd4-1660.app.omni-coder.com/public_html/functions.php on line 25