SIM7600 as RNDIS interface for Raspberry Pi

Question

I have a SIM7600 4G hat from Waveshare and a Raspberry Pi 4. Based on Waveshare documentation (https://www.waveshare.com/wiki/Raspberry_Pi_networked_via_RNDIS), I connected the hat and configured it for RNDIS communication as followed:

1. Check that the device is recognized:

   pi@pi1:~ $ lsusb 
   Bus 001 Device 004: ID 1e0e:9011 Qualcomm / Option 
   

2. I configured the hat mode with the correct PID value:

   AT+CUSBPIDSWITCH=9011,1,1
   

3. I now have a new usb0 interface with an IP address (after using dhclient -v usb0). However, reaching Internet over this interface does not work:

   pi@pi1:~ $ ping -I usb0 google.com
   PING  (172.217.168.78) from 192.168.225.44 usb0: 56(84) bytes of data.
   c^C
   ---  ping statistics ---
   3 packets transmitted, 0 received, 100% packet loss, time 88ms
   
   

The driver rndis_host seems to be loaded correctly:

pi@pi1:~ $ lsmod | grep rndis
rndis_wlan             40960  0
rndis_host             16384  1 rndis_wlan
cdc_ether              16384  1 rndis_host
cfg80211              675840  2 rndis_wlan,brcmfmac
pi@pi1:~ $ 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 1: Dev 5, If 0, Class=Communications, Driver=rndis_host, 480M
        |__ Port 1: Dev 5, If 1, Class=CDC Data, Driver=rndis_host, 480M
        |__ Port 1: Dev 5, If 2, Class=Vendor Specific Class, Driver=option, 480M
        |__ Port 1: Dev 5, If 3, Class=Vendor Specific Class, Driver=option, 480M
        |__ Port 1: Dev 5, If 4, Class=Vendor Specific Class, Driver=option, 480M
        |__ Port 1: Dev 5, If 5, Class=Vendor Specific Class, Driver=option, 480M
        |__ Port 1: Dev 5, If 6, Class=Vendor Specific Class, Driver=option, 480M

What am I doing wrong? Note that the hat can successfully send SMS, do calls and reach Internet with AT commands.

Answer 1

A couple of things:

First, verify with lsusb -t that the Linux in-kernel driver rndis_host driver is loaded correctly. You should get something like this:

/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/8p, 480M
|__ Port 4: Dev 6, If 3, Class=Vendor Specific Class, Driver=option, 480M
|__ Port 4: Dev 6, If 1, Class=CDC Data, Driver=rndis_host, 480M
|__ Port 4: Dev 6, If 6, Class=Vendor Specific Class, Driver=option, 480M
|__ Port 4: Dev 6, If 4, Class=Vendor Specific Class, Driver=option, 480M
|__ Port 4: Dev 6, If 2, Class=Vendor Specific Class, Driver=option, 480M
|__ Port 4: Dev 6, If 0, Class=Communications, Driver=rndis_host, 480M
|__ Port 4: Dev 6, If 5, Class=Vendor Specific Class, Driver=option, 480M

Second, in order to use SIM7600 in RNDIS mode, you have to configure the APN twice in slot 1 and 6:

AT+CGDCONT=1,"IPV4V6","<your_apn>"
AT+CGDCONT=6,"IPV4V6","<your_apn>"

Obs: If your APN needs aditional info (user,password, etc) check AT+CGAUTH in SIM7600 AT manual.

After you configure your APN, you have to reboot the SIM7600 or disconnect/connect to network with:

AT+CFUN=0
AT+CFUN=1 

Then try again with:

dhclient -v usb0
ping -I usb0 8.8.8.8

If you got internet connection, remember to set priority of that interface in /etc/dhcpcd.conf or maybe your wifi or ethernet connection will continue to be the default gateway (check with route)

Good luck!