Comment 55 for bug 1815101

Thank you Dan and Eric!

Summarizing howto with bionic for myself:
Upgrade systemd to the version with "keepconfiguration" fix.
Look at /run/systemd/network/*.network filename, in my example it is "10-netplan-ens160.network"
Make a directory adding ".d" to this name: /etc/systemd/network/10-netplan-ens160.network.d
Add a file "override.conf" into this directory, with content:
---
[Network]
KeepConfiguration=static
---