Finder disconnects mounted network folder after some time

1. I mounted the Multimedia folder from my Qnap NAS by dragging and dropping it to FInder's sidebar (AFP protocol).

2. I also added this mounted folder to my Login Items in System Settings so that this folder will be mounted automatically on login.

Problem:

After some time Finder drops connection to my shared folder. I can still see the folder but when I click it to access it, it takes a few seconds for finder to connect to that folder again. This creates a problem for both, iTunes and Plex since my media is stored on my Qnap. iTunes and Plex "think" that the Multimedia folder is unavailable and I have to manually click the Multimedia folder in Finder to connect to it before I can use iTunes or Plex. This is very annoying.

Is this some kind of bug, a network setting, or system setting? How can make sure that Finder always stays connected to my shared mounted NAS folder?

Thanks.

OSX - Mountain Lion
Qnap firmware version: 3.8.1 Build 20121205

I am testing my connection with NFS share instead of AFP right now. What I have noticed so far is that with NFS my mac connects to the shared folder almost instantly but with AFP it takes about 10 - 20 seconds to connects almost every time I click on the shared folder. I think that there is also a big problem with Qnap and AFP. I am not sure if SMB is better than NFS.

Any thoughts?

I ended up using this guide: http://useyourloaf.com/blog/2011/01/24/using-the-mac-os-x-automounter.html

And using NFS for file sharing.