Solid green lights indicates that your booster is functioning properly and there are no issues with installation. First, you should check and see if all cables and antennas are connected correctly and tight. Next, check on the distance you are away from the inside antenna. You may need to be closer to the inside coverage to receive signal into your device. If there’s still no improvement, try turning your Voice over LTE off on your phone. The 3G network is much wider reaching compared 4G and is the recommend setting unless you are in a major city with outstanding signal strength. Performing these checks will give the booster every chance at offering an effective boost.
Lastly, please keep in mind that boosters require some signal to amplify, if you are in a remote or rural location, with very weak or even no service, a booster will not amplify a signal from nothing!