Complete loss of wifi after connecting a wifi booster

I recently purchased a wifi booster to help get wifi in my back garden. I set up the booster using my iphone 5, (iOS 10.3.2), and now I cannot connect my iPhone to either the original router or the wifi booster, although my laptop, a computer, and other iPhones in the house connect to both perfectly. When the names of the networks appear in Settings -> Wi-Fi, "Security Recommendation" appears under the router network and booster network names, which leads me to believe the phone now thinks that they are part of an open network even though they both require passwords (lock icon still displays). Can this issue be solved through the iPhone/Apple or is this an issue that has to be solved through the configuration of the wifi booster? Many Thanks, C.