TP-Link M7450 as USB WAN gateway (RNDIS)

I have a TP-Link M7450 MiFi, and would like to connect it as a tethered USB WAN gateway to my TL-WDR3600 v1(OpenWrt OpenWrt Barrier Breaker 14.07).

The TP-Link M7450 MiFi supports RNDIS:

I followed the Android instructions in the following article:

However, the output in the kernel log after installing the packages and tethering the M7450 is:

[3296722.950000] usb 1-1.2: new high-speed USB device number 3 using ehci-platform
[3296723.830000] usb 1-1.2: USB disconnect, device number 3
[3296724.090000] usb 1-1.2: new high-speed USB device number 4 using ehci-platform

This is missing an expected, final line of output, of the format:

[ 176.654650] rndis_host 1-1:1.0 usb0: register 'rndis_host' at usb-f1050000.ehci-1, RNDIS device, ee:da:c0:50:ff:44

Is this the way that I should be approaching tethering this device as a WAN interface?

Any help greatly appreciated.

Is there a particular reason why you're running an ancient (unsupported), known insecure, 5 year old version of OpenWrt on your tl-wdr3600 and not the current 18.06.5 or 19.07.0-rc1?

The tl-wdr3600 itself works nicely with 18.06.5 or 19.07.0-rc1, there is no technical reason not to update it.