Hello mahonm2,
We see you're having issues with FaceTime calls while on Wi-Fi, and we'd be happy to help.
We'd recommend starting with this page, which can help with FaceTime call issues: If you can't make a FaceTime call on your iPhone, iPad, or iPod touch
Be sure to also check for any VPNs or networking/security apps that may be installed. If you have any installed, try temporarily uninstalling them.
You may also try resetting the network settings of the device. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before. Be sure to note down any needed Wi-Fi passwords ahead of time.
Cheers.