Hello
I am using a Zerotier on my OPNSense box and
it has two gateways.
I need my Zerotier traffic to go through one gateway among them
How can I enforce this through OPNSense setting?
You need to create a rule on the interface/zone that the traffic first touches, then specify the gateway on the rule.
Zerotier Interface, or LAN interface, depending on the source of the traffic.
Source: source subnet
Destination: Presumably any, or the destination you want to route
Gateway: Your chosen gateway