Hi all!
After upgrading to fedora 36 my modem stopped working. I tried reinstalling, but it didn’t help. Other distros have no problem picking it up and using it. After that, fedora can use it until the first sleep, then it’s broken again.
This modem is the Sierra MC7455
Is the firmware up to date of the modem?
I’m unable to update and don’t know how to check.
I tried all following this guide:
So I was able to get the firmware version:
It’s SWI9X30C_02.33.03.00
The latest version is SWI9X30C_02.38.00.00
I’ll try updating again.
So I tried updating to no avail. It seemed it worked but the update didn’t happen. I’m suspecting I have defective hardware. 
Have you checked with an F36 live system if you can use it? Or a F35 one? Just to see if it is really the hardware or just the driver.
Back with the results.
The test I did was simple.
I did them on Win10 as a fresh install, F35 (ISO v. 1.2) and F36 (ISO v. 1.5) both as live ISO-s.
Win10 and F35 succeeded both tests, but F36 failed at reconnection after suspend. After that even a reboot wouldn’t fix it. Only booting F35 or Win10 would. After that F36 could connect to the network once.
Is Bluetooth active when you goo to sleep? If yes does it need to be?
In a other topic I was reading that this caused problems.
Can you try to do the firmware-upgrade on a F35 or windows 10 to be sure it is done correctly.
I tried the FW update on F36, F35, Ubuntu 20.04 and Win10 to no avail. 
I’ll check w/o Bluetooth as it is enabled.
Update:
Disabling Bluetooth did nothing.
My device is a ThinkPad Yoga 2nd gen. if it helps.
If it helps.
I have a Sierra EM7455 with the same version in a Dell laptop. I have booted into a live Fedora36 and it works fine.
The only problem is the signal strength shown in the network settings is only 45% so it disconnects often.
I have to check if there is a new firmware available for the EM7455 version.
Can you try my test with suspending?
Thanks
What is your version?
I am on SWI9X30C_02.33.03.00
I booted using a Fedora36 live flash disk.
I have attached the dmesg output after exiting from suspend.
Well then my modem must be borked
I tried to update to the latest firmware in my Dell (Windows). There was an error downloading the firmware so the update didn’t happen and also it put the modem to a low power state, so I couldn’t use it at all.
I removed this modem from Dell and insterted it in a Lenovo (Fedora36) and updated to the latest firmware SWI9X30C_02.38.00.00
I then again tried your steps.
So in my case both firmwares worked after suspending the laptop.
I still have to check if my modem disconnects automatically due to low signal strength.
You might have also to check if there is a power saving option for the card on.
I have been using it continuously for sometime now without a single disconnection. I think, the disconnection problem was fixed by the firmware update.
I expected the signal strength to be better after the firmware update as my Huawei phone next to the laptop with the same mobile provider shows full bars.
I guess your phone has the better antenna. Or some obstacles are in the way by the laptop. The antenna is normally on the lid of the computer.
Foremost, thank you both for being so helpful 
Since I made my post, the modem just gave up on itself. The BIOS thinks it isn’t a genuine Lenovo modem… I had many problems with updating as well.
I concluded this has to be faulty hardware.
Thanks to the new company I work for, I got a new computer.
I still think the behaviour of the modem was odd and would have been interesting to debug, but sadly my laptop won’t even boot with it installed.
Now I struggle with the Quatelcel EM120 
