Running instrumental tests independently

I'm trying to run tests on a device. They are run with the help of ADB through Wi-Fi. The command I'm executing is:

am instrument -w -r -e debug false -e class package.TestClass#testMethod -e listener package.MyListener --no-window-animation http://ift.tt/2ynItrh

Now some of my tests are testing how application behaves when there is no access to internet. Unfortunately, once I switch Wi-Fi off, instrumentation stops running.

As far as I am concerned I am happy with telling the device to start running tests and then after it is done to check back on the results. These are stored in report files I generate myself.

Is there a way to accomplish this? Running tests on device connected through USB is not an option.