Update 1/18/17: Services have been restored.
OCLC is suffering major failures across multiple systems at the moment and is working to restore access. This is affecting all of their customers and products.
EZProxy, which is now hosted by OCLC (for Storrs and Regional Campuses), is also down. Access from on-campus or through SkyBox is unaffected.
No estimate on time to restoral of service by OCLC at this time.