Sharing router, crypto gateway and proxy?

Question

Computer networks

Good afternoon.

There is a network 192.168.1.0/24. It is distributed by a device to which there is no access. NAT and DHCP are spinning there for the entire range. The terminals have this device (1.1) as the main gateway. This needs to be saved.

It is necessary to introduce a crypto-gateway and UTM into this network in the gap between this router and the ends.
I see the following structure Router-Cryptogateway-UTM-End Users.

What is the best way to arrange this? We can’t climb into clients, into the provider’s router too. What settings should be on UTM and KSh?

My version: the router gives out the address via DHCP the address of the KSh in the network 1.0, the second network KSh is connected to the UTM network 0.0, then UTM gives subnet 1.0 to the clients again?