anon7, that is very strange that you are having issues connecting to the network extender with your iPhone XR. Let's work to get to the bottom of this. Based on the steps you have already taken the next thing I want you to do is reset your network settings. Once your settings have been reset I want you to reconnect to your Wi-Fi but make sure Wi-fi calling is disabled. Once you have followed those steps I want you to try making a call to see if you are staying connected. Let me know what happens.