DNS error when trying to install docked and portainer on openmediavault

when trying to install docker and portaienr on openmediavault i get the dashboard and i see the options OMV extras, correctly, but when i hit install, in the screen i get a DNS error message, i don´t know how to fix it, because i literally haven´t touched any configuration files from before installing openmediavault it on a raspberry pi 4