Mosquitto On Two Devices [SOLVED]

Might need a bit of help with mqtt with this one.
I have mosquitto running on two devices as follows: hosting OH2 (openhabian) and localbrokerrb hosting node-red running 24/7

I send mqtt messages from a couple of Sonoff devices (and some others but not relevant) and want to exchange messages with both of the above.
I want to use a rule in OH to send an mqtt command. At the command line on the OH machine this works fine: mosquitto_pub -h -t cmnd/sonoff2/POWER -m 1

But have not been able to get the rule to send the message.
The item line looks like:
Switch WT_Waterpump "Water Pump" { mqtt=">[*:default],<[]" }

and the rule :

Time cron "0 29 16 * * ?"
sendCommand(WT_Waterpump, ON)
postUpdate(WT_Waterpump, ON)

But no action results at the Sonoff. After reading the man for mosquitto I have added the two addresses to the .conf file this : address
This also does not give me the result.
Any tips on how I can work with mosquitto on two devices?

It looks like what you want to do is to configure one of your Mosquitto servers as a bridge. Google will be your friend, here just the first example that popped up:
I have ne personal experience with this, however.

@lipp_markus Thanks for the tip on the keyword “bridge”. Implemented and working nicely.