Cannot open Home-Assistant over duckdns when connect to PiVPN

Hello all,

when I connect to my OpenVPN I cannot open my Home-Assistant over my duckdns address. When I disconnect my VPN the Home-Assistant is reachable. When I connect to the VPN the connection to the local IP works. Is there a solution for it? Im using the Home-Assistant iOS app and when I connect to my VPN I cannot use the app anymore.

The Home-Assistant server is not running on the same PI where the OpenVPN server is running on.