Times out on securityheaders (SH is in DigitalOcean) [1] and qualys [2]. osdev.org is hosted in Linode. Linode status page is green [3] so perhaps an individual VM or application issue. It also appears they had a lot of services exposed to the internet including FTP, SSH, NTP, MySQL and "MBBS Socket Harness" not sure what that is, so there is a possibility.
[1] - https://securityheaders.com/?q=https%3A%2F%2Fosdev.org%2F&fo...
[2] - https://www.ssllabs.com/ssltest/analyze.html?d=osdev.org
[3] - https://status.linode.com/