404 error on redirection

We are on cloudways, and I know i have to use the Omit Port matches code into wp-config.php and that was already done to even get redirects to work.

define ('SMARTCRAWL_OMIT_PORT_MATCHES',true);

However, we had to put in redirects for every possible variation for the URL. As an example:

If I create a redirect from "something.com/about/" to "something.com/new-about/", when I access to the page "something.com/about/", it redirects properly. But If access to "something.com/about" it gives a 404 error.

So, we need to create two redirects, one with the trailing at the end of the URL and other without it.