When Generating Certs for Plex Connect you get WARNING: can’t open config file: /usr/local/ssl/openssl.cnf

You need to enter this:

Type at prompt: set OPENSSL_CONF=c:\openssl-win32\bin\openssl.cfg  (if you don't run this line you will get the following error: WARNING: can’t open config file: /usr/local/ssl/openssl.cnf

You won't get the error message any more when creating the certs.

 Source:  Link