Looking for RTFM on IP passthru. Example: cell modem gets the IP but passes public IP straight to the second router, so there is not a daisy chain.
Model ZBT-WE826 (16M)
Architecture MediaTek MT7620A ver:2 eco:6
Firmware Version GoldenOrb_2022-09-01 ( OpenWrt 19.07.6 )
Kernel Version 4.14.215
If you're using GoldenOrb, ask them, or install proper openwrt.
Does it support the modem and the APN profiles?
"proper openwrt" Does it support the modem and the APN profiles?
Yes, see the documentation for various modes here: https://openwrt.org/docs/guide-user/network/wan/wwan/start
Regarding your initial question about passthrough - the short answer is "not supported" by either OpenWRT or ROOter.
At the same time such a goal is generally achievable, but that is much modem dependant.
You can see my old example here: Using a router as "dumb" LTE gateway? - #25 by AndrewZ
Unfortunately you have provided all the information except the one that is really important - your modem model.
Modem : Quectel EP06
Reference #25. Since the router is physically next to the modem, just bridge the WAN and LAN and disregard VLAN?
Since some level of separation between the management and live data traffic is typically needed, you can bridge the WAN with either a VLAN on a shared Ethernet LAN port or with a dedicated port.
With EP06 you have a choice of QMI, MBIM and ECM modes, you can bridge only in the latter case. However, in its standard configuration your modem [in ECM mode] will act as a NAT router internally. From my understanding this behaviour could be overwritten, but that will require an access to the file system of the modem itself (via adb).