Using WAN DHCP

I just bought an RB750 and upgraded to RouterOS 6.2, I want to use it for QoS for voip for customers, most already have a network setup using the DHCP from the WAN Router.

I have setup Queues for priority and marked packages and everything seems to work, howevery all the IPs on the client’s network changed because of the DHCP on the router, they have some static IPs on some devices and reconfiguring the whole network doesn’t seem like a plan to them.

Is there a way to have the RB between the WAN and their switch and maybe use the DHCP on the WAN, so RB can “transparently” do QoS? Is this possible?

thanks in advance

it depends, if clients are connected to separate ports (one on each port) you can use interface as target to limit by QoS configuration

They would be connected on a single port. The QoS part is not the problem. Is being able to do it while having the network staying “the same” that would mean having them use the dhcp that they have now which is on the WAN router