I've installed LMS 3.1 on two Windows 2003 servers. In both cases, the LMS servers is not archiving the configurations from the majority of the devices (~600).
I've verified (via a credential verification report) that these devices are reachable from both test LMS servers. One of the test servers is in the same subnet as our production server.
Our Production LMS 3.01 server has no issues with the archives.