Open Radar

 
Summary:
If I connect a iOS device ("client") to a Wi-Fi Hotspot  generated by another device ("hotspot"), then it is not possible to do an iCloud backup of the client device. If you attempt to force the backup manually by using the button "Backup now" you will get an error message saying that the connection is not good, even if the connection is pretty good and reliable.

Steps to Reproduce:
1. set a device (e.g. iPhone) in Hotspot mode
2. use another device (e.g. iPad) to connect to hotspot set in previous step
3. go to Settings -> iCloud -> Backup
4. ensure "iCloud Backup" is enabled
5. tap the button "Back Up Now"
You will see a few seconds after tapping the button the following message below the button: "The last backup could not be connected because of poor network connection". However quality of hotspot signal is pretty good and 4G connection provided by the hotspot device is great (> 20MB upload!)

Expected Results:
I would expect the backup to be completed correctly given the fact that Hotspot provide wi-fi is pretty good.

Actual Results:
iCloud doesn't make the backup. Note that the error message appear almost immediately so it's like it's not even attempting to do it, it seems it doesn't like the Hotspot.

Version:
Hotspot device: iPhone 5SE with iOS 10.2.1
Clients device: iPad Pro with iOS 10.2.1 AND iPhone 5 with iOS 10.2.1