Hello holli164,
Are you also able to make FaceTime calls on the iPhone? If so, try the troubleshooting steps here specific to the Mac that can help with FaceTime connection issues under "If you need help with your connection or call quality": If FaceTime isn't working on your Mac - Apple Support
If not, there's an issue connecting with FaceTime from both devices that might be related to the network. Does the same thing happen when the iPhone isn't connected to Wi-Fi? You'll want to check other requirements and steps here that are also specific to issues with FaceTime and can also address concerns with your Mac getting calls from the iPhone as well: If you can't make or receive a FaceTime call on your iPhone or iPad - Apple Support
If none of the above reasons apply to you, and you still can't make or receive FaceTime calls, follow these steps:
1. Make sure that your device has a Wi-Fi connection to the internet or a cellular-data connection.
2. Learn more if you're using router, firewall, or security software that restricts internet access.
3. If you're trying to use FaceTime over cellular, make sure that Use Cellular Data is on for FaceTime. Go to Settings and tap Cellular or tap Mobile Data, then turn on FaceTime. If you're using an iPad, you might see Settings > Cellular Data.
4. Go to Settings > FaceTime and make sure that FaceTime is on.
* If you see "Waiting for Activation," turn FaceTime off and then on again. Learn what to do if you can't activate FaceTime.
* If you don't see the FaceTime setting, make sure that Camera and FaceTime aren't off in Settings > Screen Time > Content & Privacy Restrictions > Allowed Apps.
* Make sure that you have the correct phone number or email address listed.
If the type of calls you’re trying to make on your Mac are phone calls, make sure everything is still set up correctly: Make and receive phone calls on Mac or iPad - Apple Support
Kind regards.