1 Mikrotik with 2 DHCP servers 1 on ether1 the other on ethe

I have 1 Mikrotik with 2 DHCP servers 1 on ether1 the other on ether2.
Working fine, my question is, how can I block traffic so each of these networks can’t ping or see each other?
The MT is a client radio doing pppoe and then as the 2 networks off of it.

drop or reject FORWARD from one subnet to another

Okay, how would I do that?

firewall - new rule - chain = forward, in interface = ether1, out interface = ether2, action = reject, reject with = icmp admin prohibited
firewall - new rule - chain = forward, in interface = ether2, out interface = ether1, action = reject, reject with = icmp admin prohibited