FaceTime disconnects Wi-Fi during every call and reconnects automatically after ending the call on iPhone 14

Re: "Facetime disconnects wifi during every call and reconnects to wifi automatically after ending the call.

How can I fix this issue?"

Are the people you call using Apple devices, apps, and operating sustems,

or

might they be using Android phones and cellular data, or Windows computers and software

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Also: If turned on, Wi-fi Assist may switch between wi-fi and cellular data (may be a provider-cost) if wi-fi signal is not strong enough.

About Wi-Fi Assist - Apple Support

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If needed you can: "Create a link to a FaceTime call

You can create a link to a FaceTime call and send the link to others using apps like Messages or Mail.

They can use the link to join or initiate a call.

Learn how to create a link to a FaceTime call

Learn how to join a FaceTime call from an Android or Windows device

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Above is from the article: Use FaceTime with your iPhone or iPad - Apple Support

... which has much more info., tips, suggestions