In my setup i have a dedicated management interface in my setup.

My current interface configuration at Router1
WAN: Public IP with default GW per DHCP (eg 1.1.1.10/24 default GW 1.1.1.1)
LAN: Public IP subnet (2.2.2.1/24)
MANAGEMENT: 172.16.1.100/24

The management subnet is behind the public ip 2.2.2.100. So at Router1 there is a route to 172.16.1.0/20 via 2.2.2.100. There is also the subnet 172.16.5.0/24 for managing devices.

The problem is management traffic from host 172.16.5.20. Everything will be routed back to 2.2.2.100, wich is not working beause of the sateful firewall.
Is there a simple way to add an exception for routing management traffic to 172.16.1.100 (from host 172.16.5.20) back to the default GW 192.168.100.1

Is there a simple rule (policy routing?) for routing management traffic back to a specific gateway?

Thank you

Draw a diagram I am confused when you show one WANIP address and then in the text refer to a different WAN interface.