Attempted to call function "idn_to_ascii" from the global namespace when trying to use Mail methods in Prestashop

I am receiving a 500 internal error in Prestashop whenever it comes to using the inbuilt PHP mail() method. After enabling debug mode, I found that the cause is this:

(1/1) UndefinedFunctionException

Attempted to call function "idn_to_ascii" from the global namespace.

in Mail.php line 893

I googled this issue as it is most probably common and was hit with a GitHub issue https://github.com/PrestaShop/PrestaShop/issues/10640 which states that the php-intl extension is needed.

I SSH'd into my VPS and ran sudo apt install php7.3-intl since the PHP version I use is 7.3. This worked fine and installed the extension. However, after restarting the Apache2 service like so: sudo systemctl restart apache2.service. I am still hit with the same error message.

I have tried editing my /etc/php/7.3/apache2/php.ini fine to include the extension=intl on the autoloading but this did not fix my issue either.

Any information or help appreciated in advance.