I shared this info with my hosting company and they replied:
I’m not sure how to get your plugin to look for the correct root certificate. They are all up-to-date.
The server certs are fine (we’re running Windows Server 2008). But my website/domain doesn’t have a SSL certificate at all. I could purchase but since my site doesn’t have sensitive information this might be a bit overkill. Is there a workaround?
