LE Cert does not work with various Yealink phones

The Let's Encrypt process built into Certificate Manager creates certificates that will not work with Yelaink phones in the T4xG line. Some firmware versions of the T$xS line were also affected.

A cert from GoDaddy (and others) works just fine, as does a Certbot created cert on the FreePBX 14 system that is manually imported.

Community thread for reference from October of 2017: https://community.freepbx.org/t/yealink-t4xg-phones-will-not-autoprovision-over-https-with-freepbx-14/44617