(os-sftp-backup) not working through VPN

[SchengFui]

Hi there,

i'm struggeling with the OPNSense SFTP-Backup through an VPN-Tunnel (OpenVPN and Wireguard, IPSEC not testet).

I can Ping and Traceroute the SSH-Server from the OPNSense itself, however ich have to specify the Source IP (LAN Interface). Without this, both fails.

When testing the configuration-backup i can see Packets with a strange Source (10.22.101.0:26140) on the remote Firewall, this is the OpenVPN-Transit-Network for the VPN-Connection.

Is it possible to specify an outgoing IP-Address (or Interface) for the sftp-backup?

What else can i try?

Thank you!