Thanks for all of the updates and feedback, guys.
In short, I didn't make any changes per se. I did take steps to diagnose the server to make sure there were no issues in respect to the operation of the server, including to make sure there were no vulnerabilities. I found nothing out of the normal.
I contacted the hosting provider and made them aware of the issue. Their initial response was that they were not aware of any issues. I suspect that the problem was with the hosting provider or their infrastructure.
Feel free to contact me if you notice future problems. Sorry for the slow downs over the previous days.
Shane