The extended Internet downtime at Michigan, which appears to be a lockdown after a security intrusion, appear to me to highlight some issues with the Handle system, the underlying technology for DOIs, identifiers in repository systems like Dspace, and volume links in #Hathitrust.
The Handle protocol is pre-REST, and typically uses its own ports (usually 2641 or 8000). If you're locking down a network, it'll probably be a while before you get to start unblocking specialty ports like those. Plus…