Networking Basics Labs - Switching and Routing - Last Question

Hi all,

Im connected to app03 and trying to Add a routing table entry in app03 and app04 hosts so that these hosts can reach app01 and app02 hosts via jump host .

But on app03 when im running this command its giving error
[thor@app03 ~]$ sudo ip route add 172.16.239.15 via 172.16.238.1
RTNETLINK answers: Network is unreachable

How can i resolve this issue??