Hey there,
make sure both devices are up to date. On the new iPhone you can use: Update your iPhone, iPad, or iPod touch
On your android device , are you using any network monitoring apps, like a Wi-Fi Analyzer? If so, you'd want to remove them and try the transfer again.
If that doesn't help try the steps in this article ☞ Move content manually from your Android device to your iPhone, iPad, or iPod touch
You can also try removing all saved Wi-Fi networks on your android device your , then try again.
if you still need help Contact Apple for support and service - Apple Support