LTE connection established but no data once PPP session created


Background: I have a Nova U-201 & Raspberry Pi which uses a service called Radioroom to send MAVLINK messages (a protocol for drone communication) from a drone to an amazon server and then a PC ground station can connect to the server to access this information. This entire chain of communication works when I use Wi-Fi, my intention is to do exactly this but over the network provided by the Nova.

Issue: My Nova can successfully ping google / can download small amounts of data (e.g. curl IP address) but as soon as a PPP session is created (and the pppd process is started), I see no data from my drone. If I were to reconnect to Wi-fi and restart the service, it would still not work. It is only when I kill the PPP session ‘sudo hologram network disconnect’ that data starts to appear again (when the pppd process is killed).

The problem persists when connecting solely through the LTE module with no connections to Wi-fi being made. When I connect to the network and show a verbose output I can see the modem using /dev/ttyACM0 and /dev/ttyACM1. My initial thoughts are that once this serial connection is created to the modem, this is interfering with my serial connection to my drone, however, I can still print the data from my drone to the terminal and so it looks like this connection still exists.

So I guess my question comes down to: why would my service run fine through Wi-fi as well as a mobile hotspot, but not through the Nova? (I am able to ping / download so signal appears to be okay and each message I am trying to send is only 64 bytes). Also, on the hologram dashboard I can see I am using my data.

Edd (a Linux beginner).

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Hi @Edd,

Any luck with this? I have a friend working in a project who is suffering from what seems to be the same problem and I was wondering if you had any updates?

If not, has anyone else in this amazing community got any suggestions as it is really hampering my friend’s productivity?

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