Dns issue when connecting to sys-vpn

inside sys-vpn, all requests work fine
however, when using qubes that have internet provided by sys-vpn, nothing works. no requests go through

i suspect this to be a dns issue, yet have no idea where to look

work → sys-vpn → inter (to be able to set firewall rules) → sys-whonix → sys-firewall → sys-net

any idea?