Hi Shaker, welcome to the forums!
It sounds like the integrated NIC on 3 of your newer motherboards are not compatible with the Fog kernels you are trying to use. Have you tried any of the 3.3 or 3.4 kernels?
The RTL8111 seems to use the same linux drivers as the RTL8168, and have been around since 2008, so a kernel somewhere should support them.
If not, you can customize your kernel for Fog by using steps similar to those I followed and documented in: [url]http://fogproject.org/forum/threads/compiling-a-custom-kernel-for-acer-iconia-tab-copied-from-old-forums.216/[/url]
If the configurator already has a section for the RTL8111 or RTL8168, then it’s as easy as overwriting the files in the source tree and recompiling the kernel.