I have a private Apache server, reachable only from my LAN on port 443, with a StartSSL certificate.
Since Firefox 51 was released, I cannot connect to it any longer as the StartSSL root certificate was removed from the trust store.
I considered migrating to Let's Encrypt, but that appears to require a public-facing HTTP server. Is it possible to use Let's Encrypt in my situation?
I would rather avoid paying for an SSL certificate, if at all possible.