I recently upgraded my iPhone 4 to IOS 6.1.2. The immediate result was a loss of connectivity between the phone and MFT. The solution to the problem that I found is to :
1.) Delete phone from MFT.
2.) On iPhone, go to Setting, then General, then Reset, then Reset Network Settings.
3.) Re-pair iPhone to MFT.
Worked for me. Hopefully it will work for you if you are experiencing the same connnectivity problem.