First - don't ever mount your drives manually. LMCE does this automatically - if it does NOT, then there is something else wrong that needs to be fixed first, mounting manually will almost certainly break your installation unless you know LMCE and autofs, etc intimately.
If you have 2 NICs available to you, go back and try again getting that working. Networking is almost certainly your problem, and going to single NIC will make that worse unless you know exactly what you are doing (or you are following the Wiki article on single NIC installations!)
LMCE expects to have its own "internal" network available to it that is controls and provide DHCP for. If it has this, then the network PlugNPlay will work much more reliably, as you initially found out.