Raspberry Pi 400 + 3G-4G/LTE Hat = no bueno

Hi there - I was able to get thru the introduction, and what ostensibly looked like success from a SW/HW perspective is nothing of the sort. I’ve got a Raspberry Pi 400 + 3G-4G/LTE HAT, and hardware wise I have a solid red/blinking blue light. On the portal I’m able to see my device, but it’s connecting only via wifi - I’m not getting wwlan0, nor dev/modem/ nor (from what I’ve read from other posts) anything registering at all via USB. I’ve even run a separate power supply to the modems microusb, but while lights blink there is nothing visible to the OS. From what I’ve read before, here’s some initial diagnostic output :

uname -a : Linux raspberrypi 5.15.76-v8+ #1597 SMP PREEMPT Fri Nov 4 12:16:41 GMT 2022 aarch64 GNU/Linux

root@raspberrypi:/dev# lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 04d9:0007 Holtek Semiconductor, Inc. Raspberry Pi Internal Keyboard
Bus 001 Device 003: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

root@raspberrypi:/dev# lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M
|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
|__ Port 3: Dev 3, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
|__ Port 4: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
|__ Port 4: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M

root@raspberrypi:/dev# cat /etc/os-release
PRETTY_NAME=“Debian GNU/Linux 11 (bullseye)”
NAME=“Debian GNU/Linux”
VERSION=“11 (bullseye)”

/dev/modem doesn’t exist

Hi @agrignon,

Can you test with another USB cable? If possible can you also test your HAT with RPi 3/4?

Hi, I have the same problem: nothing under lsusb and lsusb-t regarding wwan or anything related to modem. Is there any solution? Or still waiting for answer from support?

Hi agrignon,
My problem is solved. I guess you may have done like me: forgot to connect the short USB cable between your RPi USB port and the HAT USB port. Now I can see the USB related drivers and online I can see wwan0