ip route add fails with next hop invalid although next hop on directly connected network

Question

When I check the routing table I get following information:

root@vmi24:/home/user# ip route
default via 194.104.212.225 dev eth0 onlink
194.104.212.224/27 via 194.104.212.225 dev eth0

When i want to add a route to 10.0.0.0/24 via 194.104.212.226 (which is part of the directly connected 194.104.212.224/27 network, I get following error:

root@vmi24:/home/user# ip route add 10.0.0.0/24 via 194.104.212.226
Error: Nexthop has invalid gateway.

Another strange issue is that if I delete the default gateway, I cannot add it again because the add command for the default gateway fails with the same "Nexthop has invalid gateway" error.

I am using Debian 10 on a hosted VM.

When I try this on a KALI based machine have no issue adding a static route.

I am running out of options, as this phenomenon prevents me from activating an openvpn (it fails inserting the /32 route to the openvpn server via the directly connected gateway on the eth0 interface

What do I fail t see? What do I overlook? I have found many problems with next-hop documented but most if not all are due to not directly connected or unreachable next-hops.

Regards

Patrick

Solution

you have to use "onlink" too, like so:

ip r a 10.0.0.0/24 via 194.104.212.225 dev eth0 onlink

because the net 10.0.0.0/24 and default gw are outside of all known local networks. you probably have to configure network routes back to your host as well?! looks a bit strange to me, at least for IPv4 .. with IPv6 this would be ok. hopefully it works for you!

HTH