Why can't I link my Iphone to my Ipad via bluetooth

Miwestcoast wrote:

connection failed Device not supported.

That's right. Apple has never supported Bluetooth connection between iPhone and iPad. Instead, Apple supports Continuity and you can learn about that here --> Use Continuity to work across Apple devices - Apple Support

iPhones and iPads do not support Bluetooth pairing with each other.

In addition to working together using the Continuity features that lobsterghost1 mentioned, iPhones and iPads can work together through iCloud synchronization, shared e-mail accounts, and third-party cloud services. (Note that calendars can be associated with e-mail accounts and synchronized that way.)

iCloud+ - Apple

Set up iCloud on all your devices - Apple Support

Apple has never supported the type of connection that you are asking about.