I'm so sorry to hear you are having trouble with the wifi-calling but I am here to help! There aren't any current known issues on the device that would be causing this problem. To best assist I wanted to ask you a few questions to start and I will follow up with you as needed.
1. Can you connect to the same Wi-Fi network with another device or computer?
2. Are you within 15 feet of the router while testing?
3. Are there walls between the device and the router?
Thank you so much in advance.