Failed to connect to FTP Server ftp.(mywebsite):21

We recently upgraded our hosting account to the latest PHP version and from Windows to Linux so we could install our WordPress website.

However, when trying to install a plugin or update in our WordPress Dashboard, it gives an error:

Failed to connect to FTP Server ftp.(mywebsite):21

We are using the below credentials. It works fine while trying to connect with an FTP client but not in our WordPress.

Also, We are having problem with other sections, such as uploading files in our gallery.

Is this a server sided problem or a bad configuration in my WordPress files?