We need to work with more than one APN working at the same time and on the same 3G/4G modem or SIM. Will this be possible? Thanks.
No (that's not possible on any device) - but you can change APNs just like on any other device.
Not true. This is very much possible with many common modems. Most (all?) MBIM modems support it and all newer QMI modems. You can only attach to one network of course, but often to as much as 8 APNs. Not that I think most people will have a use case for that
MBIM modems witll report "maxsessions" when asked about their capabilities. This one supports 8 APNs:
# umbim -p -d /dev/cdc-wdm0 caps devicetype: 0003 - remote cellularclass: 0001 voiceclass: 0001 - no-voice simclass: 0002 dataclass: 003C smscaps: 0003 controlcaps: 0001 maxsessions: 0008 deviceid: 014582000xxxxxxx firmwareinfo: SWI9X30C_02.38.00.00 hardwareinfo: EM7455
The modem module in the NR7101 supports 15(!):
# umbim -d /dev/cdc-wdm0 caps devicetype: 0001 - embedded cellularclass: 0001 voiceclass: 0001 - no-voice simclass: 0002 dataclass: 8000003C smscaps: 0003 controlcaps: 0001 maxsessions: 000F deviceid: 35435111001xxxx firmwareinfo: RG502QEAAAR11A07M4G hardwareinfo: RG502Q-EA
Some modem firmwares have an artificial restriction where the modem disconnects active sessions when you connect a new APN, even if the modem could support multiple APNs. I believe this is intended as a feature, assuming that users rather want to switch APNs than connect to multiple APNs.
For Sierra Wireless modems like the EM7455 this feature can be disabled by
Multi APN connections require IP session multiplexing. This is supported in the cdc_mbim driver using a weird VLAN to MBIM Session ID mapping, and in the qmi_wwan driver using the even weirder sysfs QMAP interface. It's also possible to use the rmnet driver on top of qmi_wwan in passthrough mode.
But I guess most users will want some tool to simply set up the muxing. The good news is that ModemManager can do this for you. Simply add "multiplex=requested" or "multiplex=required" to the mmcli --simple-connect parameter along with APN etc. The bad news is that this isn't integrated into the OpenWrt ModemManager scripts yet, AFAIK.
This is what I meant.
thanks for the reply