I think we've determined it's not a hardware problem. We see TX bytes being sent, and from your system log, it looks like the net interfaces are driven by the Linux huawei_cdc_ncm driver. We can also see your modem attempting to communicate. If you want to rule that out completely, you should:
- check the firmware version (needs to be 21.xxx.xx.xx.xx);
lsusb on your router and check for USB ID 12d1:1506
- Check the current mode by sending the AT command
AT^SETPORT?. You'll be looking for mode 16 for NCM and 1 for 3G
I do rather suspect it's a config problem, though. I've had similar problems, and I've first tried to get it working attached to my computer which is why I suggested that. A search of the internet should help if you're not sure how.
Finally, you could try getting it to work in 3G mode first, and then trying NCM. E.g.:
config interface 'modem_1_1'
option ifname '3g-modem'
option service 'umts'
option apn 'ctlte'
option proto '3g'
option device '/dev/ttyUSB1'
option dialnumber '*99#'
option metric '40'
option disabled '0'
See https://openwrt.org/docs/guide-user/network/wan/wan_interface_protocols for other options, in this case.