Cannot connect to VPN when using iPhone hot-spot

I am using a HP laptop which is connected to the internet using my iPhone 6s (iOS Version 13.2).

When I try to connect to VPN (forticlient 6.0.5) I get to 98% and nothing happens. I have experienced this issue with multiple iPhones so it is not just my iPhone.

When I try to connect to VPN using an Android or other WiFi networks it connects fine.

All the iPhones have been on the Telstra network.

Of the Androids that were tested, one was Telstra and one was Optus.

Most of the users experiencing this issue have been using HP laptops however one user was using a Macbook Pro 2018 15inch

I tested on an old iPhone SE with iOS 10 on it and I was able to connect to VPN using my own simcard that does not work in my iPhone 6s with 13.2 on it.

Is anyone else experiencing similar issues with iOS 13?