After experimenting with the suspend features I found that after waking the phone (pressing the power button for a about a second) the mobile connection usually does not restore. Sometimes it does and I’ll check it by verifing that it will successfully fetch data. When the mobile connection does restore it’s usually after waking from the very first suspend session on a given boot. It seems anytime after the first one it won’t do it again. The worse part is wasting the time thinking it’ll eventually connect.
So there’s two things you can do besides hoping it wakes correctly. One, don’t put it in suspend mode or 2, after waking(with no cell connection) just be done with it and take the 45 seconds to go through the boot process.
But I found something that works for me everytime. After it comes out of suspend, swich off the cell modem. Purism usually says wait 10 seconds. Then turn on the Calls app. It’ll come on with the red banner saying you have no connection. We know that. Then turn on the modem switch. I’ve found it comes on every time and takes about 15 seconds total. Best thing is that there’s no guessing what it’ll do.