TFS 2012 Test Agent keep alternating status Online/Disconnected

Question

TFS 2012 environment
Test Controller and Agent Update 3.  
We are using a shadow account to connect the Agent (not on domain) to the Controller (on domain).
The problem I'm having is that the Test Agent Status alternates constantly between Online and Disconnected. 
I have all TCP and UDP ports open in the Firewall on the Agent and Controller (can't just turn it off because of policy settings).  
I have created an environment in Lab Center and can kick off a Lab Template based build definition to execute an automated test.  The process get to a point of wait for the the test environment to be ready, starts a test execution, and completes the
test run with a Warning: "An error occurred while communicating with Agent vstfs:///LabManagement/TestMachine/###", where ### is a three digit number.
If I just sit and watch the Test Agent status, with no test runs running, the status will show Online for about 10-15 seconds and then show Disconnected for about 30-60 seconds.  And then it repeats.  
Another thing to mention, the Test Controller for this effort was cloned from a previous Test Controller that was used for another project.  The previous Controller was on the domain at the time of being cloned and had issues of being the same computer
name on the network and then other issues because the Controller was already assigned to a collection.  Another person here went through a process of fixing by uninstalling the controller software and then deleting some XML files that were left behind
after uninstalling the controller software.  I feel that a new controller should be created from scratch because I feel that there is still some conflicts between the old and new Controllers.
Any assistance would be greatly appreciated.

Answer 1

I have additional information to supply to this thread for the benefit of others who may come across this issue.
The main issue of using the same version of Test Manager with the version of TFS you have running is the first part.
After this post, I added additional testing environments and virtual machines in SCVMM and started having the "Online/Disconnected" issue again.  With more research, I figured out that I had to add the IP address and host name of
the Test Controller to the hosts file on the Test Agents (path to the
hosts file "C:\Windows\System32\drivers\etc\").  Just open this file in NotePad (or the editor of your choice) and add a line at the end with the IP and host name.
Example hosts file:
# Copyright (c) 1993-2009 Microsoft Corp.
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
# For example:
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# ::1 localhost
123.456.78.9 computername.domain.com
I have used this several times and it has worked every time (so far) where I use shadow accounts in the TFS test environments.  Hope this helps!