More information would be very useful. What we currently have is the equivalent of my car is making a funny noise.
What version of calibre?
What operating system and version? Windows, MacOS, Linux?
Are you setting your Kindle Fire to MTP mode when connecting to the computer?
If yes, do you see the storage mounted on your operating system?
Have you tried a different USB cable or port?
Email would be for send to Kindle use and requires some setup.
When you used calibre server, did you attempt to connect to the address and port shown in the server configuration page? I.e.
http://10.244.152.23:8080 for example.