I ran sudo iptables -t nat -I PREROUTING -i ens3 -p TCP -d 209.182.233.167/32 --dport 80 -j DNAT --to-destination 10.23.133.117:80 (Notice I used ens3 where I had previously used eth0.) and now it works.
I don’t get the significance of ens3 vs eth0.
While I was waiting to be able to reply, I read a few articles which seem to indicate ens3 is replacing eth0. I don’t know how this will be significant, bu at least now I know I need to get that info (eth0 vs ens3) from ifconfig to use in the iptable rule.