From what I remember Let's Encrypt does not yet offer wildcard certificates. But my memory is faulty. First hit using Internet Search Engines with Code: Let's encrypt wildcard on record dns is https://letsencrypt.org/2017/07/06/wildcard-certificates-coming-jan-2018.html which states
Let's Encrypt now supports it, but ISPConfig does not yet. You could manually issue the certificate, which is done via DNS auth - this thread has some related info: https://www.howtoforge.com/communit...lidation-in-acme-v02.79049/page-2#post-389604
I have been using dns-challenge for wildcard LE certs since a year ago with custom vhost config but with the latest git-stable (as discussed in the thread mentioned above), you may not have to use custom vhost config anymore. Simply issue LE certs using dns-challenge manually, then create the website for the said domain and tick LE SSL, but do remember that for *.domain.tld, certs are issued and kept under domain.tld folder. I believe in version 3.2 dns-challenge will be supported by ISPConfig, at least it is already in its plan.
