trying to use USB connection, easytether-usb and Ubuntu 18.04.2, error = interface is used by another process (hotplug?)

Question

The Set Up

• Phone - Moto z3 - developer mode ON, debugging mode ON
• easytether - v 1.1.19
• Ubuntu - 18.04.2

Actions taken

1. installed easytether Pro
2. installed drivers (easytether_0.8.9_amd64.deb) dpkg -i easytether_0.8.9_amd64.deb
3. ran following cmd sudo easytether-usb returns error message

interface tun-easytether is used by another process (hotplug?)

What I've Tried

1. Restarting both phone and laptop.
2. Turned wi-fi on and off
3. Restarted the network manager sudo systemctl restart network-manager.service
4. Restarted the ModemManager sudo systemctl restart ModemManager-manager.service
5. Even though it states it's for 16.04 I added source-directory interfaces.d to my etc/network/interfaces file.
6. As per easytether pro documentation tried running the following commands

# systemctl enable systemd-networkd
# systemctl start systemd-networkd

systemd-networkd not found?

The questions

1. Is it an issue that the interface tun-easytether is being used? If it is how can I find out whats engaging it?
2. If the process lock isn't my issue, where should I logically looking?

Answer 1

Went over the easytether-pro documentation again and under Ubuntu 18.04 it instructs user to enable/start systemd-networkd

sudo systemctl restart systemd-networkd.service

This time I used the command-line completion on the string "systemd" and one of the results were systemd-networkd.service

Having the '.service' at the end seems new to 18.06.

Anywho I'm on the lines which is what matters. Hope this helps others.