Blame the laws of physics. If the tower and device antennas are located too close together, they will pick up each other's signals and create a feedback loop, a condition called oscillation.
Oscillation left uncorrected can damage the cellular network. For this reason, the FCC requires all signal boosters to auto-detect oscillation. When oscillation is detected the signal booster, by FCC regulation, will shut down immediately.
Oscillation-caused booster shutdowns can be prevented by locating the tower and device antennas far enough apart, which weBoost refers to as the Minimum Required Separation Distance.
The Installation Guide that came with your signal booster explains the MRSD for your specific booster model. If needed, you can download an Installation Guide from your booster's product page at www.weboost.com/us.
Generally speaking, for a booster that provides 50 dB of gain, or signal boost, the antennas need an MRSD of 40 feet. For a 60 dB booster, the antennas' MSRD is 75 feet.
A roof or wall between the two antennas may reduce their MRSD.
FAILURE TO OBSERVE MRSD WILL RESULT IN YOUR SIGNAL BOOSTER SHUTTING DOWN. IT WILL NOT RESTART UNTIL THE OSCILLATION CONDITION HAS BEEN CORRECTED.
To learn more about how antennas work watch this short video.