How to route traffic to a gateway on a VPN network?

I'm in a Docker container, on a host connected to a remote network via VPN, and want to route all traffic to 10.43.0.0/16 to 10.148.185.170 (host on the VPN network). sudo ip route add 10.43.0.0/16 via 10.148.185.170 dev enp0s5 Error: Nexthop has invalid gateway. $ ip route show default via 10.211.55.1 dev enp0s5 proto dhcp metric 100 10.211.55.0/24 dev enp0s5 proto kernel scope link src 10.211.55.3 metric 100 169.254.0.0/16 dev enp0s5 scope link metric 1000 172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown The error I get is that "Nexthop has invalid gateway", which probably means I cannot specify 10.148.185.170 as the gateway, since it's on the VPN network and requires an extra hop (VPN TUN interface)? If that's correct, **how can I tell the operating system to send network packets to 10.43.0.0/16 through the VPN network with 10.148.185.170 as the gateway**? **Note**: All traffic from the container to hosts on the VPN network are notmally routed correctly, e.g.: $ nc -vvv 10.148.185.170 443 Connection to 10.148.185.170 443 port [tcp/https] succeeded!