In the center of the network switch, L2+ enough or do you have L3. It will be terminated at all client Alans, and it also start Ulanova on the interface with ip address - this is getway for each subnet.
AECOM on the switch configure DHCP-Relay (l2+ usually) for each VLAN.
Then make the default route on your router that will natite all your network.
The router routes in response to each subnet.
If the hands are too lazy, do dynamic routing is a good choice.
In the end of the network run on L3 there or in neighboring or VLAN on the router and to the Internet depending on request.
The Dhcp server could be anywhere, he'd pass it on relay.
If you need redundancy router - buy 2 router, configuring vrrp. Either do 2 routes with different weights - vrrp is better of course.
The switch is reserved for more complicated and more expensive then if you simply do crowns Tusk which dampit config, destroys and commits in the git repo.