TRM500 as Cellular Backup on a router

Networking Solutions
1

Hi Community,

I have a Zyxel EX3600-TO as a router for my fiber connection at home. It supports cellular backup on its USB port. So I bought a TRM500 to use for this purpose.

Now the problem is that the router doesn’t even recognize the TRM500 when I connect it, it doesn’t sense anything being connected. When I connect it directly to my laptop (Win 11) it works well.

Any suggestions what to do?

Kindly, Mikael

2

Hi,

Probably doesn’t recognize because drivers needed? On Win11 most of times it automatically install needed drivers.

Most of these routers give list of supported/tested USB modems.
Probably you should try to write to Zyxel support or forum for help.

Link to TRM500 drivers:

3

Thank you Lemondude. The drivers on the link are only for Windows and Android, no Linux.

Yes, I am looking at Zyxel too, the other side of the problem.

My simple guess would be to find a way to make the TRM500 act like a modem, so that no drivers are needed on a Linux environment.

5

Hello, @Ryking ,

I’ve reached out to our R&D to ask about this and will get back to you once I have more details.

Thank you for your patience,
M.

6

Hello again, @Ryking ,

The R&D has inquired about the Zyxel router that you own. Specifically, they would like to know:

  1. What operating system does the device use
  2. What data protocols does it support (e.g., RMNET, ECM, MBIM, RNDIS)

They’ve also mentioned, and I quote:
If it's a Linux-based system and the RG520N-EB module's VID:PID is not recognized by the kernel serial driver, the user might need to manually add the VID:PID using: echo VID PID > /sys/bus/usb-serial/drivers/option1/new_id
(Replace VID and PID with the actual values for the module.)

Regards,
M.

7

The modem supports both USB Ethernet mode’s I.e. RNDIS or ECM, with those you should be able to connect to any router wich supports USB networking.

If the router has support for Microsoft’s MBIM or newer but possibly slightly better QMI than the router can make a connection by themselves without the overhead of Ethernet in between.

The downside with the first solution is that there will be a Nat unless you enable IP pass through, I.e. IPPT.
IP pass through is a little buggy sadly, sometimes it doesn’t pass on the IPV4 address to the router.

8

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