Why does a SIM not work with a 4G Router (ZBT WE-2608)?


I can't use a specific SIM with openWRT in a ZBT WE-2608 which has two slots.
I have successfully used a Swiss SIM in a in Switzerland.

Now I've tried an Italian SIM (from Very Mobile) in Italy.
It works in a different 4G modem from Huawei, but not in ZBT-WE-2608.

I've set the APN to internet.it as it says in their documentation.
Still doesn't work.

Are there more settings for SIM cards?
Might there be a block from the network operator?

Same issue with zbt we-826.
Nothing related with openwrt neither zbt hardware.
Instead is my EC25 lte modem inside the router.
With firmware EC25EFAR06A06M4G_01.006.01.006 working like a charm with 3 LTE networks in Portugal. ( Meo, NOS, Vodafone ). But same router configuration and LTE EC25 with a newer firmware ( can't remember correct version ) Meo ISP SIM card, don't get a valid gateway or return error in connection.
Try to contact Quectel ( if your lte card is a Quectel ) and explain your issue.

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The modem module and its firmware controls the link to the 4G network. The SIM card slot is connected to the modem module, not the router CPU. OpenWrt has very little to do with the link other than basic configuration of the modem.

It's usually best to start with APN unset, so the modem uses the preferred APN stored in the SIM card. This works with most modern modems and carriers.

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Do you mean something like:
option apn 'unset'
in the modem section of the network config?

Don't place an option apn line in the section at all.

Have you check what default APN is configured in the modem?
You can check with at-command :at+cgdcont? or with qmilci, if your modem support QMI.