Yesterday,  I took my Advanced and 4 batteries on a road trip.  On the first flight,  it took 3 tries to connect to my Samsung Galaxy S5.  My Nvidia 8inch Shield tablet never did connect.  On the second flight,  it took over 10 tries for the S5.   The other 2 batteries I never got to use,  because they would not connect.  I tried 4 different usb cables.   Once I got back home,  I connect the devices up to my computer using the same cables.  The device would then give me the option to change the usb connection type.  I would select "Connect as MTP"  and then I was able to connect to the Phantom.   
This behavior happened with both Litchi and the Go app.
4 different cables.
2 different apps.
2 different devices.

In every case,  once I connect the device to my home computer,  I was able to change the connection type to "Connect as MTP".

In every case,  changing to MTP allowed the device to connect to either the Go app or Litchi ,  using any one of the cables.

In every case,  I could only connect 1 time,  then I would have to connect to the computer again.  Every time I did this, I would find that the device was connected as "Installer" on both devices.  Changing to MTP would again allow me to connect 1 more time.

I am at a loss as to what is going on.  This was rarely a problem for me until recently.  It has gotten progressively worse.
The only common denominators I can see are:

The R/C physical connection to the device.
The computer connection to the device
The DJI SDK used in both the GO app and the LITCHI app.
The Android operating system on both devices.

While in the field,  in order to force the connection to happen,  I would try all combinations of ways to start the system, device, controller and aircraft.  There was no one way that would work consistently in any situation.  Seemed to be pure random luck as to whether or not it would connect in any given situation.

I know,  from being on here for about a year,  that the "No connection " issue seems to have been getting more common.  I still have no real clue as to what the problem is caused by.  Does anyone else have any thoughts on this?

Hi Kneepuck, which android version are you on? Have you killed other apps running in the background? I've asked because there's a member here not being able to connect, as it seems that some background apps are actually hiding while running and trying to connect to the AC simultaneously, thus made the "no connection" issue. One even said to get an app killer, which is an app too.

Hello Kneepuck, does the IOS DJI GO app (non-SDK version) work well on your RC?

vandruten Posted at 2016-6-19 10:56
Hi Kneepuck, which android version are you on? Have you killed other apps running in the background? ...

I'm on the latest.  And the only thing I use either of these devices for is to fly my Phantoms.  I always configure for no background apps in the developer menu.  These devices don't even have sim cards and wifi is always off.  And they were working fine for almost a year.

DJI-Paladin Posted at 2016-6-20 02:29
Hello Kneepuck, does the IOS DJI GO app (non-SDK version) work well on your RC?

I don't have an Ios device to try on them.

Yesterday I went to the same place to try again. Neither device would connect at all,  so I ended up flying blind and shooting video anyway.   Don't even ask how it came out.

Are you on the latest FW?

Ok,  so the problem is associated with the Hdmi module.  I removed the Hdmi module from the r/c and installed the original usb port back in.  Everything works fine now.  So,  for anyone have connection issues,  if you have an Hdmi module installed,  try going back to the USB module.

Kneepuck Posted at 2016-6-21 03:18
Ok,  so the problem is associated with the Hdmi module.  I removed the Hdmi module from the r/c and  ...

Glad you got it figured out, they do go out but I've only seen a very few USB ports go bad. Call 818-235-0789 and they will take care of it for you. It has a 6 month warranty.

DJI-Ken Posted at 2016-6-20 13:39
Glad you got it figured out, they do go out but I've only seen a very few USB ports go bad. Call 8 ...

Ha ha,  just my luck.  I'm out of warranty.  Oh well,  guess I'll be ordering a new one.

Kneepuck Posted at 2016-6-21 05:57
Ha ha,  just my luck.  I'm out of warranty.  Oh well,  guess I'll be ordering a new one.

Ahh geez, sorry about that.

I can now say for certain,  it is the Hdmi module,  at least in my case.  I did repeated test.  All I have to do is remove the cover from the hdmi module,  not the whole module,  and it works as it is supposed too.  Put the cover back on,  no connection.  Did this at least 5 times.  Same results every time.

Hey, i have the same Problems with fresh mounted HDMI-Module. When i remove the 4 Srews and remove only the cover i can use the usb-Port like without HDMI-Module

72er Posted at 2016-6-21 11:21
Hey, i have the same Problems with fresh mounted HDMI-Module. When i remove the 4 Srews and remove o ...

Exactly the case with me.