Hi, first post!
Okay so, I just bought Zorin 17 Pro and started the upgrade, mid-upgrade I noticed that I was using my cellular data hotspot, so I switched to a faster Wi-Fi.
After doing that I checked if it was still pulling data, but it was barely doing so.
Here is a screenshot of the System observer (or however it's called in English).
Hi and welcome to the forum. Can you check whether Software Updates source setting is a regional/national server. If true, change that to "Main Server", which is usually considered the best choice for all users.
EDIT: I misread Upgrade as Update. My words above refer to Software Update not version Upgrade e.g. Z17 Core to Z17 Pro as you are attempting.
Can you see the Software Upgrader app screen?
Has it thrown an error due to interruption from you switching from cellular hotspot to wifi?