How to isolate networks with a Mikrotik router?
Solution 1:
Indeed, Mikrotik devices does routing automatically between networks. Consider the two networks 10.0.0.1/16 and 192.168.1.0/24, for example. If you want to block traffic between those two, just add two firewall rules
ip firewall filter add chain=forward src-address=10.0.0.0/16 dst-address=192.168.1.0/24 action=drop
ip firewall filter add chain=forward src-address=192.168.1.0/24 dst-address=10.0.0.0/16 action=drop
so you drop packets in both directions.