Routing IPv4 via IPv6 IPsec Tunnel

[mwiora]

Hi @all,

I've configured a native IPv6 IPsec tunnel.
Now I want to tunnel IPv4 over that IPv6 tunnel - this should be possible, shouldn't it?

Site A:
Dualstack IPv4 (172.16.0.0/24 locally) + IPv6
SiteB:
Dualstack IPv4 (172.17.0.0/24 locally) + IPv6

unfortunately I'm receiving:
Nov 20 02:01:55 charon: 07[KNL] installing route failed: 172.17.0.0/24 via fe80::3631:c4ff:fe83:a04a src 172.16.0.1 dev hn1
Nov 20 02:01:55 charon: 07[KNL] adding PF_ROUTE route failed: Invalid argument

Thanks for any reply in advance!
Matthias