Trying to configure cpanel caldav doesn't seem to work.
Could not resolve host: mail.xxx.xx: at /www/html/Modules/LJPcCalendarModule/vendor/sabre/http/lib/Client.php:356)
Could not resolve host sounds like a DNS issue, so that would not have anything to do with this extension. Try pinging the host via the machine that freescout is running on.
Trying to configure cpanel caldav doesn't seem to work. Could not resolve host: mail.xxx.xx: at /www/html/Modules/LJPcCalendarModule/vendor/sabre/http/lib/Client.php:356)