Before I start I will say I am not well schooled in Ubuntu and spend the majority of my time using Windows devices, this is something I am working on rectifying though! I am encountering a bit of a strange issue. I am running a virtual machine on VMware. The operating system is Ubuntu 18.0.4. When I do a
ip route
I get the following output.

default via dev ens160 proto static dev docker0 proto kernel scope link src linkdown dev br-4b2ad03c78f9 proto kernel scope link src dev ens160 proto kernel scope link src
First of all I don't understand why or where the route is coming from. This route is causing me issues. It is forcing me to manually add a route in order to get the box to communicate with the subnet. If I do the following it routes fine to the subnet which is as expected.

 sudo ip route add via dev ens160
However every couple of weeks this route disappears and I have to go back into the box to add it again.

So I guess the questions I have from encountering this situation is the following:
1. How do I add the route to keep it persistent?
2. How can I find out why or where the route is coming from?

Any help or pointers on this would be greatly appreciated.

Kind regards, Joe.