Recently we had a report that an application running on a partner's server was no longer able to send requests to Blackboard's Learn servers. They were SOAP requests - which is being deprecated - but that wasn't the issue.
We've moved our servers to TLSv1.1/1.2. We're also using a modern set of ciphers. Make certain you're using both and you'll be able to connect!
Here's one article that describes a symptom and solution for those using Microsoft .Net libraries.