I just installed Let's Encrypt certificates on two machines recently and apparently everything is working correctly.
The two machines (iMac, and MacMini) use High Sierra MacOS.
One of the machines (iMac) hosts just one site.
The other (Mac mini) hosts three sites.
Looking at the access_logs, there are differences I don't understand.
The iMac (one site only), appears to call regularly /api/passphrase and /api/license/timestamp/ which are noted with a code 404.
::1 - - [16/Feb/2021:02:46:36 +0100] "GET /api/passphrase HTTP/1.1" 404 212
::1 - - [16/Feb/2021:02:46:37 +0100] "GET /api/license/timestamp/53a4c0c0e4b0f503bd6e4368 HTTP/1.1" 404 244
::1 - - [16/Feb/2021:03:45:17 +0100] "GET /api/passphrase HTTP/1.1" 404 212
There are no such connections in the MacMini log (which hosts many sites).
What could be the problem ?