For calibre to convert DOC format to other formats, you need to install the
Microsoft Doc Input Plugin. And this needs a tool from Microsoft to do part of the conversion. The details of this are in the first post of the thread. I don't know if this will solve the problem with reading them through the server.
But, if you can, it is better to use DOCX. The support for this is built into calibre and it works better than the above plugin.