Be extremely careful when using the ELM crappy SFTP interface. I have noticed an issue where the SFTP will go belly up when trying to transfer large period of times (e.g. a full month worth's of logs).
The server will not crash, instead it will fail to render the synthetic file list you download files via SFTP (i.e. \\BrowseByDatasource\Device-Name\Year\Month\Day\Hour\timestamp).
According to McAfee this is as designed and the SFTP interface is not supported for that sort of use (you couldn't invent such a b**** excuse for a poorly developed product).