[arm-allstar] Connection fails from one end only

[David]

We use a hub to link repeater 1 and repeater 2 together using all 
private nodes.  All the servers are Rasp Pi3 running v1.5.  Now I am 
trying to add repeater 3 and link it to the hub.  Of course I think I 
have the [nodes] info in rpt.conf configured correctly at both ends.
  Here is my question:
I can connect (using Supermon) repeater 3 to the hub from repeater 3 
server but not the other way around.  I have used Zoiper to connect to 
repeater 3 successfully to confirm the port is open.  What have I missed?
- Dave k6dvd