Make sure you are using the correct app. For the Marksman, Hawk and LR-3 for newer phones and tablets please use the Longshot App on the Google Play Store or Longshot HD for Mac.
For the LR-2 or users with older phones or tablets, please use the Targetvision app.
Turn off the power to the Marksman.
Wait one minute then restore power.
Wait two minutes then retry connection.