missing gw in route -n

[Gene Heskett <gheskett@shentel.net>]

Greetings;

I have been playing the 10k monkeys scene trying to figure out how to add 
a gateway entry to the route -n report on a rock64 with a stretch/xfce 
install on it.

Where does this assignment belong in a static defined eth0 configuration?

I know several places where it doesn't work, but what I need to know is 
where do I put, in what file, the "gateway = www.xxx.yyy.zzz" and make 
it just work for a stretch install on a rock64.  Thats an arm64 family 
card.

All I have been able to get out of route is the gibberishy help when 
there is a syntax error.

The obvious (to me that is) place would be 
in /etc/network/interfaces.d/eth0, which has this:

auto eth0
allow-hotplug eth0
iface eth0 inet static
address 192.168.71.2
netmask 255.255.255.0
gateway 192.168.71.1
dns-nameserver 192.168.71.1

But that is ignored.

Help please.

Thanks.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>