Comment 3 for bug 1781203

The parameters are supported; but you cannot "try" that configuration out temporarily. The 'try' subcommand attempts to keep the current configuration around, generate and apply the "new" config, and allow you to confirm if things are working and if not, it will restore the original config prior to the try. One cannot "try" bond or bridge parameters. However, you can still use those parameters but netplan won't be able to roll-back the changes automatically.

If you instead run:

% netplan apply

This will generate configuration for the network backend and then apply those changes to the system immediately.