cURL not found

I am running the enterprise server V5.4.5 on Ubuntu 18.04. I recently upgraded my server from 16.04. I had compiled PHP 7.4.3 through the LiteSpeed console, but it is not finding the curl extension. A phpinfo() shows the --with-curl, but the section on curl itself is not shown and, of course, curl cannot be accessed. It I do an apt-cache search lsphp74-curl, nothing is returned. Am I missing a repository or ??? If I change the configuration to use the previous versions of PHP (7.2 and 7.0), curl is missing from them also. When I tried recompiling PHP 7.4 using the console, it fails with the error "No package 'libcurl' found" (but libcurl4 is installed).

I figure I must be doing something obvious wrong, but it escapes me...