Maybe. You also may want to do a force restart first. Maybe even a dfu restore. Instead if jumping in and replacing the antenna. You also may want to try toggling airplane mode, off and on
怎样强制重启 iPhone 6
Plug your device into your computer with a USB cable.
Turn off the device.
Hold the Power button for 3 seconds.
Hold the Home and Power buttons for 10 seconds.
Release the Power button but keep holding the Home button.
Hmm, kinda surprised they don't have a guide for this. Remove the logic board using this guide, then remove the antennae on the back
iPhone 6 主板更换
iPhone 6 Logic Board Antenna Flex Cable