vlan tagging on subinterface

Hi all,

I have an srx running on a customer site and i want to add a virtual interface with a vlan tagging on it.

My experience with Pfsense or Sophos UTM or VyOS is that i can create a virtual subinterface on a logical interface (L3) and give this new subinterface a Vlan tag

In Junos i am not able to achieve this

fe-0/0/7 {
 unit 0 {
 family inet {
 address 192.168.0.254/24;
 }
 }
 unit 30 {
 vlan-id 30;
 family inet {
 address 192.168.30.1/24;
 }
 }
}

fe-0/0/7 is the lan interface and this cannot have a vlan tagging because the local network has to reach this ip

When i set vlan-tagging on fe-0/0/7 i have to give unit 0 a vlan tag but my network is not sending any tags so my router becomes unreachable.

So what i want to achieve is  unit 0 untagged and unit 30 tagged so i can run a dhcp server behind unit 30 so it won't affect unit 0

There are multiple platforms  that  can do this easily so i am sure Juniper should also be able to achieve something like this

Regards,

Robbert