A red light indicates a feedback loop condition called oscillation. To fix this, simply move the antennas further away from each other then reset the booster by powering it off and back on. If you still see red lights, you may have to move them even further away until you see green lights. You always want to check your signal after every test to see if the amplifier is working for your device.
If for some reason you moved the antennas and are receiving red and green blinking lights, check your signal on your cellular device and check if the signal has improved. Red and green lights are fine as long as your amplifier is working and offering you enough coverage inside your home or office. This will not damage the booster or its components.
If you still cannot receive the desired separation or if you feel like there's enough separation and the lights continue to flash/be solid, please reach out to us at 866-294-1660 or contact our online support at: firstname.lastname@example.org