Can't get internet connection with LTE-M modem

mobileSIM · 12-09-2021, 09:57 AM

Hello,
I am working with a raspberry pi 3 B (raspberry Pi OS) and the SIM7070G LTE-M modem with a LTE-M SIM card. Configuring the modem via at commands I can get an internet connection and ping e.g. google.com. Now I'm trying to set up a ppp connection on my RPi via the modem. I added the ppp/peers/SIM7070option file and the ppp/SIM7070-chat.dat file. Than I call "pppd call SIM7070option" which adds the ppp0 internet adapter to ifconfig with the following output:

Code:

ppp0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 100.97.4.210  netmask 255.255.255.255  destination 10.64.64.64
        ppp  txqueuelen 3  (Point-to-Point Protocol)
        RX packets 10  bytes 313 (313.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14  bytes 408 (408.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

The IP routing command give the following output:

Code:

ip r
default dev ppp0 scope link
10.64.64.64 dev ppp0 proto kernel scope link src 100.97.4.210
route -n
Kernel IP routing table
Destination     Gateway     Genmask             Flags Metric Ref Use Iface
0.0.0.0         0.0.0.0     0.0.0.0             U     0      0   0   ppp0
10.64.64.64     0.0.0.0     255.255.255.255     UM    0      0   0   ppp0

I think 10.64.64.64 is just a default address that the Pi gets because it doesn't find a valid end for the ppp connection.

Does anybody work with the same modem and can tell me what configuration I have to change?

Thanks

ondoho · 12-12-2021, 04:44 AM

What sort of device is this? A link with specs, maybe?
Is that the only network connection?
Have you tried installing NetworkManager and ModemManager to see if it Just Works?

mobileSIM · 12-12-2021, 10:36 AM

This is the device: https://www.waveshare.com/wiki/SIM70...B-IoT/GPRS_HAT
I shut the eth0 connection down so currently it is the only internet connection.
Haven't tried the network manager yet but will try it.

ondoho · 12-18-2021, 01:09 AM

Ah, it's one of those raspi plugins.
Re-reading your 1st post it seems that the modem works, you just need a way to automate the creation of your internet connection.

I'm not sure about your 'ip route' output (it looks like a different version of ip than mine), and 'ifconfig' doesn't even exist on any of my systems anymore (I guess it's 'ip link' now).
But always good to specify what is "not working" - can you ping numerical IPs?

It's a long time since I set up a ppp connection, but have a good look at this article. I also used wvdial at some point.

edit:
obviously you should also look around how other SBC users realized mobile broadband internet connections.
Just saw something right here on LQ.