Unconsistent cellular connexion and delay to switch from BaseSation to Zero tier with BlueBoat cellular modem (EG25-G)

Blue Robotics Vehicles BlueBoat
1

Hello there,

I’m experiencing some strange behaviour with the BlueRobotics cellular modem and I’d like help find its origin.

The cellular link does work, but switching from the BaseStation to the cellular connection over ZeroTier is extremely slow, it takes several minutes before BlueOS becomes reachable again over cellular. That delay is my main problem.

Setup

  • BlueBoat, BlueOS on Raspberry Pi 4 (Navigator)
  • BlueBoat Cellular Modem kit (Quectel EG25-G), Cellular Modem Manager extension
  • SIM from Matooma (POST Luxembourg, M2M), APN “postm2m.lu” (IPV4V6, context 1)
  • Remote access via ZeroTier

Symptoms

  • Cellular Modem Manager, serving cell info: RAT LTE, STATE: NOCONN, RSRP between -90 and -108 dBm
  • Netlight flashes quickly and steadily
  • NETWORK tab shows no assigned IP
  • Connection test from the extension fails (timeout) or is very poor

Questions

  1. Has anyone got a Matooma M2M roaming SIM working on the BlueBoat EG25-G? Any provisioning gotchas?
  2. With STATE: NOCONN while registered and a correct APN, what is the recommended way to confirm and trigger PDP context activation from the Cellular Modem Manager? Does the extension enable data roaming by default?
  3. Is forcing IPv4-only advisable on the EG25-G, and can it be done through the extension?

Kind regards,
Théo David

2

Hi @Eloi -

The behavior of switching between WiFi to Cellular via ZeroTier is inherently going to take 1-5 minutes, this is a known issue that has been discussed extensively here. There is no real way around it - other than using multiple control devices, each using a different link, so no switch delay is present. I typically use a cellphone connected to the system via zerotier / cellular for immediate control when the system is transitioning from BaseStation to ZeroTier cellular.

This delay occurs because ZeroTier always finds the shortest route between your devices. When the BaseStation is being used for the connection, this is a much faster route between the two devices than one over the internet. When this connection is lost, a new route is found - this is the time consuming aspect.

As for your questions, using that SIM should just be a matter of setting the correct APN for the carrier. The extension should automatically connect once properly configured.