Apache server

• Create a new file with name: .htaccess (no extension) in the root directory of the phpFox site. 
• Go to Admin CP, choose Short URLs from Settings menu. Copy auto-generate rule in this page and paste to .htaccess file.

• Click to button "Enable Short URLs".
• This rule works on most Apache servers. If it does not work, you can try this rule:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
RewriteRule ^index.php/(.*)$ [L]

• If it still not working, you can submit a ticket, so we can check detail on your server

Nginx server

After following this tutorial Install phpFox on nginx server, you just goto AdminCP -> Settings -> Short URLs, then click to button "Enable Short URLs".