6s phone reception

Am with Verizon with weak signal outside and deadzone inside. I use a (zBoost) signal booster with an external antenna (directional-- YAGI) that worked well (3-5 dots) with my Apple3 and Apple4 phones. Dual band booster for 800 and 1900 MHz. Upgraded the Apple4 to 6S (last month) and I am back...