iPhone Bluetooth Pairing Unsuccessful with iPad Pro since downloading iOS17.4

Mail messages do not directly transfer or synchronise between devices. Instead, mail messages are downloaded by each device from your Mail Provider's mail server.

As for Bluetooth pairing of an iPad and iPhone, while technically possible, it is generally pointless. It certainly has no place or benefit in downloading Mail from a mail server.

If your intention is to use Cellular Hotspot features of your iPhone, this link is optimally achieved using the native WiFi hotspot connection - this being a largely automated process. Hotspot connections over WiFi offer substantially greater throughput, range and reliability.

How to set up a Personal Hotspot on your iPhone or iPad – Apple Support

If you still wish to pair your iPad and iPhone over Bluetooth, you first need to manually enable the hotspot feature on your iPhone:

Settings > Mobile Data > Personal Hotspot > Allow Others to Join - set to ON

Next, Bluetooth for both the iPad and iPhone must be placed in Discovery mode:

Settings > Bluetooth (accessing this page will automatically place the device in Discovery mode)

Whilst both iPad and iPhone are in Discovery mode, you can mutually pair the devices.

Again, I must stress, unless you have an unusual “edge case”, pairing of iPad and iPhone over Bluetooth has no benefit.

It seems like you're facing issues with your iPad and iPhone after updating to iOS 17.4. Here are some quick steps to try:

Mail Sync Issue:

• • Check mail settings on iPad.
  • Remove and re-add Google account.
  • Consider using Gmail app temporarily.

Bluetooth Pairing Issue:

• • Ensure Bluetooth is on for both devices.
  • Restart devices and try pairing again.
  • Reset network settings if needed.