How do I get HL7588 to allow incoming connections on Linux?

I’m running Raspbian on a Raspberry Pi Zero W and trying to interface to the HL7588 on the NimbeLink 4G LTE, currently through their development kit (but hoping at some point to just wire straight to the modem module USB pins and cut down on some size).

  1. When I connect the modem via USB for the first time, ModemManager attempts to communicate with it and can get some basic details like IMEI, SIM, number, signal strength, but I can’t get any data from the internet.
  2. When I disable ModemManager and dhcpcd and instead set up the modem myself (scripts attached), I can at least get a connection to other sites on the internet and I can upload, but I can’t make anything connect to me. iptables is set to allow by default, I can make things connect to me over wifi (SSH, web server, video feed, etc.) but when I disconnect wifi and connect through the modem, I get nothing, not even a ping response.

My preference would be to get it to work nicely with ModemManager (I really like the idea of just having all that info available to me in a D-Bus API). Failing that, I guess I can keep rocking my homegrown scripts. Most important, though, either way, I would like the ability to connect to it from another computer. I’d like to serve web APIs that can be accessed at any time without having to try to pass it through a middleman server (or at least, with the only thing the middleman server does is exchange keys and point the user app to the right IP so they talk directly from there on out).

Any ideas? Am I even asking the right question?
modem.chat2.txt (51 Bytes) (222 Bytes) (1.14 KB)

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Thanks & Regards,

Does that service actually allow incoming connections?

Do you have a Public IP address?