Dude 3.6 Agent on RouterOS 6.0 RC actively refusing Client

Hello,
We are experimenting with RouterOS 6 (RC).
We have it running and all seems ok with basic configuration.
We have installed teh dude package, but are getting the error “actively refused connection” in the Dude client when trying to connect to the Dude Agent directly.
It does not appear to be a routing issue as we can use torch to see the inbound DUDE request from the client to the agent (via winbox connected to agent host system)
Traffic is going in both ways.
But for some reason this routerOS wants to block this traffic.

All other routes to (on all other ports) to the same WAN interface on this RouterOS (which has the 3.6 dude agent installed and enabled) work fine. So it seems it some type of configuration issue on the routerOS host itself (the host with the 3.6 dude agent and 6.0 RC)

Any pointers are greatly appreciated.
Thanks
Sean