iPad unable to join iPhone hotspot

I have just updated my iPhone 8 plus to the latest software ios 15.3.1 and ever since the update my iPad is now saying unable to connect to “Cai’s iPhone”.

Has the latest software now stopped my iPad from connecting to it via hotspot?

My iPad is quite old, it’s either the iPad 2 or 3 and running on ios 9.3.5 but I’ve never had this issue before since updating my phone.

Any help?