What connection does iPhone Hotspot actually share>

Many have asked – here and elsewhere - what the IP address of a device (i.e., iPad, MacBook) is when connected to an iPhone’s Hotspot.

The answer is always the same:  just as a device connected to a WiFi Router has the public IP address of the Router, a device connected to an iPhone’s Hotspot has the public IP Address of the iPhone.

Without a VPN running on the iPhone, this is certainly true.

However, run a VPN on the iPhone, then this is no longer the case.

When a VPN is run on an iPhone, the iPhone’s IP Address changes to that assigned by the VPN Server, and its location changes to the location of that server.  However, the IP address of (say) an iPad connected to the Hotspot of an iPhone running a VPN does not change – it remains that of the original IP address of the iPhone before the VPN, and the location remains that of the iPhone’s ISP (i.e., iPhone's local mobile network provider).

This puzzles me.

Running a VPN creates an encrypted private connection – in effect, a “tunnel” - between two devices.  So, in the case of an iPhone running a VPN, the iPhone is connected to the VPN server via a “tunnel”, through which ALL data exchanged between iPhone and VPN server travels.

This is the whole point of a VPN:  to provide a private, secure connection between two devices for ALL data exchange between those devices.  That is why companies employ them for remote workers to securely connect to a company’s private internal network.

My understanding is that the iPhone’s Hotspot shares the same connection to the “outside world” as the iPhone itself uses.  This allows other devices to connect to the “outside world” using the exact same connection.

However, this does not seem to be the case.

iPhone WITHOUT VPN and shared Hotspot; iPad connected to Hotspot:

On both iPhone and iPad run Safari and go to a “What is my IP address site (e.g., nordvpn.com)…

• • Both iPhone and iPad return the same IP address assigned by the iPhone’s ISP x.x.x.x and the local location of that ISP.

iPhone WITH VPN and shared Hotspot; iPad connected to Hotspot:

On both iPhone and iPad run Safari and go to a “What is my IP address site (e.g., nordvpn.com)…

• • iPhone returns the IP address assigned by the VPN y.y.y.y and the location of that VPN server.
  • In contrast: iPad returns the same IP address and location as pre-VPN x.x.x.x and the local location of iPhone’s ISP.

But how can this be?

The Safari’s request (i.e., data) from the iPad for “what’s my IP address”, travels over the iPhone’s Hotspot WiFi signal to the iPhone, and then over the iPhone’s connection to the “outside world”, which is supposed to be the iPhone’s connection to the VPN server.

However, this cannot be the case.  If it were, then such a request on the iPad would return the exact same IP address, and location, as the iPhone.  But it did not.

So, what is happening?

It must mean that the Hotspot remains connected to the iPhone’s local ISP outside/before the VPN connection, whereas the iPhone itself uses a different signal/connection direct to the VPN server.

If this is not so:  then why/how do the iPhone and iPad return different IP addresses and locations?

Surely, this defeats the whole point/purpose of a VPN and raises the questions:  

• • what actual data, and when, does the iPhone send over the VPN?
  • perhaps more importantly, what data does the iPhone not send over the VPN?
  • how/why does the Hotspot connection differ to that of the iPhone itself?

I’d be very interested to hear from anyone who can explain what is happening here and the answers to those questions.

Please note:  The resolution, if required, is simple: run VPN on connected device (i.e., iPad).  However, I am not seeking a resolution - I have one - but an understanding of what is happening here and why/how an iPhone’s Hotspot connection is seemingly different to that of the iPhone itself.