Rpi based IPFire between isp modem and home router with existing vlans

Dear all,
I have a home network based on openwrt running inside my dlink router.The router has decent capbility but nothing super strong. In the current setup I have created some vlan based network partitions of my wifi network, each vlan covering a different ip segment(refer digram of current setup.

now I want to introduce IPFire between the isp modem and my openwrt wifi router. The bare minimum IPFire features I plan to use are:

Deep Packet Inspection
Intrusion Detection and prevention
Web filtering and AdBlocking
Monitoring and N/W Analysis(per device)
Tor client
and more in future…

My doubt is, can I have an architecture like below? If yes What would it mean for DHCP on IPFire?If I just let my wifi router acuire ip address fro IP fire, can I still have proper monitoring, VPN etc in IPFire ? Any guidance is highly appriciated.

(Ok, being a new user i am not allowed to upload second media. Please see my comment below for expected setup)

Thanks in advance.

Expected Setup:

Leaving aside the rest of the topic.
If VLAN4 is to have a private IP, I would suggest changing it to the correct value. e.g. 172.31.7.xx



good point. However the ranges that I have mentioned are a bit randomized from what I actually use. I did not check their validity post that.

No expert here.
But IPfire is only going see one device on its LAN. Your router OpenWRT.
Someone correct me if I’m Wrong.