How to load rndis_host module on usb plug-in

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Thanks to both responders to this thread. Your kindness is appreciated.
I have learned that RNDIS module is required for usb tethering on older android phones (in my case a 4 year old LG V30 running Android 9) but that the RNDIS module is not automatically loaded because the protocol is known to be insecure.
To enable RNDIS (and usb tethering) do: sudo modprobe rndis_host
To allow automatic loading of the rndis_host module on start up of USB tethering

  1. copy the file “50-blacklist-rndis.conf” from /lib/modprobe.d to etc/modprobe.d and
  2. edit the file to comment out (#) the line “blacklist rndis_host”

I did this but wrongly assumed that the process had failed when USB tethering did not seem to work. I should have checked if the module had loaded. It had.

Before USB plug in (top 5 lines) :~ # lsmod
Module                  Size  Used by
af_packet              53248  4
rc_dib0700_rc5         16384  0
qrtr                   20480  4
ns                     32768  1 qrtr
dib7000p               45056  2

After USB plug in (top 5 lines) :~ # lsmod
Module                  Size  Used by
rndis_host             20480  0
cdc_ether              24576  1 rndis_host
usbnet                 57344  2 rndis_host,cdc_ether
cdc_acm                40960  2
mii                    16384  1 usbnet

So, something else was causing the connection to fail almost as soon as it was established.
An Internet search suggested three other useful lines of investigation.
a) ensure that usb debugging is enabled - it is;
b) ensure that the phone’s MAC address is OK - it was not - I set it to Random in NM; and,
c) ensure that ModemManager.service is not switching NM settings from ‘wired ethernet’ (the setting required for USB tethering) to Mobile Broadband (the setting required for a USB cellular wireless dongle) - it was, so I did “systemctl stop ModemManager.service” to suspend the service.
These additional steps seem to have resolved the problem. I now have what seems to be a stable ‘USB Tethering’ connection .
I regret that the subject of this thread has proved to be a bit misleading. A simpler title like “KDE USB Tethering” may have been better. Please amend it if that would be useful.

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