Error: The request was aborted: Could not create SSL/TLS secure channel

I am suddenly getting the error above on my winhost app. It just started Monday night (10/12) or Tuesday morning (10/13). I am trying to grab data from another site. It was working previously for quite a long time. No changes were made by me. (Some were made just now to try to fix it).

The relevant function works on my personal test machine, just not up on the winhost site.

I'm just a retired hobbyist programmer, so I don't know much about this, but at some point I did add the following two lines to the appropriate code:
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

The app throws the error on the next line:
bWebData = wc.DownloadData(sURL);

Maybe somebody has an idea as to why this suddenly would happen with no changes in the code. I appreciate any thoughts in advance. Thank you.