So you’re actually "putting it to sleep", when you put it to sleep.

What does "never wakes up" mean? I thought I had the same problem but then I discovered that closing and opening the lid is the only way to get it to wake. Neither the power button (it turns it off) nor keypresses (they do nothing) work.

I think I tried everything, from buttons to lid to magic network packets. Once in S3 it's dead Jim, and there's nothing in the BIOS to change that behavior.

The irony is that I have a 4 years old XPS 13 where everything works like a charm, even under Linux. Talk about progress ...

I’ve had a problem like this with my XPS and I was able to solve it by holding the power button for 25-40 seconds to reset something:

https://www.dell.com/support/kbdoc/en-us/000125880/how-to-re...

A comment above mentions manufacturers removing S3 support from their bios with the exact symptoms you mentioned

I have an XPS 9500 and it sleeps+wakes, as expected, with S3.