Comment 3 for bug 1756590

After some more discussion with the netplan team, we decided to deprecate the 'gateway4/6' fields in favor of using 'default' routes. The 'to: default' stanza was introduced to the routing configuration, which is a shortcut that works in the same way for IPv4 and IPv6.

The documentation was updated accordingly, and if somebody uses the (now deprecated) gateway4/6 fields it will still work, but print a warning.

https://github.com/canonical/netplan/pull/216

This is available as of netplan.io 0.103