Nrf9160 - modem shell with ppp

[RobertLukan]

I am trying to connect RPI(and/or Nvidia Jetson) with nrf9160 custom board(Icarusv2). I am using this custom board for other purposes and it works fine. For now I found only one possible option to connect 9160 with RPI(Nvidia Jetson) over UART connection with PPP. I have been trying to use Modem Shell example and it is working fine without PPP enabled. Once I enable PPP the connection to NRFCloud goes down and I cannot understand why. 

I have also tried SLM(Serial LTE modem) application, but I could not even establish LTE connection with that example when I added PPP options. I gave up on this example as it has less features comparing with Modem Shell. 

I have been using example from 2.6.0 and 2.6.1.

So I would be interested why MoSh example stops providing LTE connectivity once PPP is being established. Also some more general idea how to connect RPI(or Nvidia Jetson Dev kits) with NRF9160. 

[RobertLukan]

I am attaching the trace:

mosh:~$ ping -d 8.8.8.8
Initiating ping to: 8.8.8.8
Source IP addr: 100.85.246.88
Destination IP addr: 8.8.8.8
send() failed: (-22)
RRC mode: Idle
send() failed: (-22)
send() failed: (-22)
send() failed: (-22)
Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)
Pinging DONE
mosh:~$

mosh:~$ ppp down
PPP net if down
PPP carrier OFF
Closing PPP zephyr sckt
PPP carrier OFF
Closing PPP modem sckt
PPP: stopped
[00:02:38.260,467] <err> net_sock: invalid access on sock -1 by thread 0x20012658

mosh:~$ ping -d 8.8.8.8
Initiating ping to: 8.8.8.8
Source IP addr: 100.85.246.88
Destination IP addr: 8.8.8.8
RRC mode: Connected
Pinging 8.8.8.8 results: time=0.295secs, payload sent: 0, payload received 0
PPP in dead phase
Pinging 8.8.8.8 results: time=0.103secs, payload sent: 0, payload received 0
Pinging 8.8.8.8 results: time=0.077secs, payload sent: 0, payload received 0
Pinging 8.8.8.8 results: time=0.131secs, payload sent: 0, payload received 0
Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 77ms, Maximum = 295ms, Average = 151ms
Pinging DONE
mosh:~$

[JONATHAN LL]

Thanks for all the info, will look in to this issue and report back.