Why does my iPad 8th Generation not update using hot spot WiFi from my iPhone 13 Pro Max?

You cannot use a WiFi hotspot from a cellular phone service connection.

You will need to find a location that uses a direct Wifi network signal to do ANY Apple iOS/iPadOS upgrades/updates.

Sorry & Good Luck to You!

There’s a huge clue on your screenshot…

Immediately below the Download & Install button, you will see the statement “This update requires a Wi-Fi network to download and install…”

Unlike recent version of iOS for iPhone, where some system software updates can be performed over a cellular network connection, iPad and iPadOS requires a WiFi connection to perform the update.

That is just a WiFi signal the Hot Spot, in your phone, generates.

The main Intenet data transmission is still over a cellular phone signal/network.

As such, Apple does NOT allow this with iPads.

It is NOT a true direct WiFi signal from a wireless, WiFi MODEM/router box network setup.

You will need to seek out a location that offers true, direct WiFi signal communiication from a local networked WiFi MODEM/router box either from a Home wireless WiFi MODEM/router network or locations that offers a free WiFi connections.

Sorry and Best of Luck to You!

A standard WiFi connection connects directly to a broadband/internet service. A WiFi “hotspot”, while using a WiFi connection to the host device, is still routing network traffic via the cellular network connection.

For various technical reasons, including but not limited to network routing - your iPad will not download, verify or install the system software update over the cellular hotspot connection routed via the iPhone.

If instead you have a Cellular Router (often known as Wireless Broadband - or MyFi), then it may be possible to perform the update over a Cellular connection. The broadband router will require a DataSIM; most mobile phone SIM cards are unsuitable, as they are not correctly provisioned for tablet and broadband router devices.

Got your additional response.

The reason Apple doesn't allow cellular service to be used for downkoading and installing iOS/iPadOS upgrades/updates is because cellu;lar service can be spotty and unreliable in many areas, depending on locations of signal towers, which can cause data drop outs/data corruption which could render a device corrupted and possibly a dead or “bricked” device, depending on where in the upgrade/update process the device is at.

This can, also, happen with a direct WiFi connection, also, but it is less likely if the connection is a consitently strong and constant signal, but if any WiFi signal degradation occurs and.or a very slow WiFi data connection speed occurs, this can, also, cause data transmission issues,,such is the case when using sattelite dish services for Internet access with a WiFi router or in an areas that use slower data tramsmission lines that may, also, be less than reliable for large data size transmission.

Lots of different global variables going on around the world.

Downloading and verifying large chunks of data over a cellular service data connection can just be even more unreliable depending on location of cellular service and signal towers.

So, Apple had to male a global decision for all on whether a critical piece of important operating software should rely on cellular service data transmission, or not, for constant, consistent transmission of large chunks of important mobile device system data.

Not everywhere in the world has the best wireless data transmission infrastructure in place.