TRM500 options and upgrade

NETWORKING SOLUTIONS
1
  1. How can I change USB-mode? If I understand this correct, it is possible to change between different modes?

"Notably, the USB Type-C interface of this 5G modem can play the role of a virtual network interface and enable simultaneous network data transmission and powering of the TRM500. This makes USB Type-C a truly flexible interface.'2

  1. Is there any know router with support for this modem? I found that OpnSense doesn’t seems to work well with this modem in serial PPP-mode. Or is there other settings or mode with better countability?

  2. Where can I find firmware update?

2

Hello,

To clarify, the USB Type-C interface on the TRM500 modem is not user-configurable for selecting different roles manually. Instead, the USB interface is designed to serve multiple functions, such as providing both power and enabling cellular network connectivity simultaneously. Specifically, when connected to a host device (such as a computer), the USB port that supplies 5 VDC can power the TRM500 while allowing it to provide a network connection via cellular data. However, this functionality is automatic and does not require manual role selection.

As for firmware updates, unfortunately, you will not be able to manually update the modem’s firmware version via the USB interface.

Best regards,

4

My use case may be odd, I´m looking for 5G connection to a remote site that is served by OpnSense running as a VM in Proxmox. When buying TRM500 I thought it was a router that I could configure as a bridge and just passthrough wan-address to OpnSense. But when I got it I realised that it´s a modem, anyway a modem should be enough for my use case so I decided to give it a try.

What I didn´t know before is that OpnSense support for modems isn´t so great. I never been working with modems so I have just made research on Internet to try to figure out about AT-commands and PPP configurations.

This info may be outdated, but it refers to that OpnSense only supports “serial PPP” and not modern LTE protocols such as QMI or NDIS. I´m not sure what this means?

After some more research I found that it´s may be possible to change usb-modes. But it maybe isn’t meant to be changed for me as an end user?

Info from: GitHub - iamromulan/RM520N-GL: Quectel RM520N-GL Resources
"

  • You can view what USB mode the modem is in with the AT command: AT+QCFG="usbnet"
    • To set it to a particular USB mode:
      • AT+QCFG="usbnet",0 (NDIS/QMI) (TE) (Default)
      • AT+QCFG="usbnet",1 (ECM) (AP)
      • AT+QCFG="usbnet",2 (MBIM) (TE)
      • AT+QCFG="usbnet",3 (RNDIS) (AP)
        "

For example if I set it to “usbnet”,3` the modem shows up as ue0 interface and gives me a ip 192.168.225.128 so modem seems to do nat. This may work but I would prefer if it could passthrough LTE-wan address instead.

Can I break something when fiddling around with various AT-commands? Is it possible to reset to factory settings with AT&F and will it set back to Quectel default or to Teltonika default settings?

5

Hi,

If it’s not possible to update firmware via USB, the question is still how to update the firmware, if there is a need? Any kind of serial TTL interface, JTAG, something else?

6

Hello,

It’s not possible to update the modem firmware on the TRM500 device using AT commands or UARTs, as it already comes equipped with the latest RG520-N modem firmware.

If you have any further concerns, feel free to reach out.

Kind regards,

7

Finally I found a solution for connecting modem to OpnSense, due to lack of modem support I had to change to USB-ehternet mode.

AT+QCFG="usbnet",3

And the changing setting to passthrough wan ip.

AT+QMAP="MPDN_rule",0
AT+QMAP="MPDN_rule",0,1,0,3,1,"FF:FF:FF:FF:FF:FF"
AT+qmap="ippt_nat",0

Not fully tested, but seems to work ok for now except for one thing. Every full hour I lose about 10-30 ping in a row.cI haven’t found anything on router side, Is there any debug options on modem side?