Log in to the forum with the administrator's user name and password, and enter the "Management Center";
Click "Background - Interface - Navigation Settings - Main Navigation";
Click "Add Main Navigation" to create a new navigation column with the name "Forum" and the link "/". As shown below:
Set the default forum page forum.php as the home page, but set it to "unavailable". Set your new "forum" to "available". Then "Save".
Click "Global - Domain Name Settings - Application Domain Name - Default" to write the domain name of your website. As shown below:
Click "Tools" to clear the website cache.
Through the above settings, we remove the suffix of forum. php. If there is a suffix after opening, it may be caused by the browser cache. You can clear the browser cache or open the website with another browser to test.