Listening on multiple IPs and routing to defferent serial port sets

I have a server with two NICs 10.xxx.xxx.9 and 10.xxx.xxx.10 and I am trying to setup hub4com to route incoming and outgoing traffic on port 4001 of the 10.xxx.xxx.9 NIC to one set of COM ports and incoming and outgoing traffic on port 4003 of the 10.xxx.xxx.10 NIC to a second set of COM ports.
The commands I am using are:
Start-Process -FilePath "C:\hub4com\hub4com.exe" -ArgumentList "--bi-route=0:All --use-driver=tcp 4001 --interface=10.xxx.xxx.9 --write-limit=100000 --use-driver=serial --octs=off --baud=600 \.\CNC1A01 \.\CNC1A02 \.\CNC1A03 \.\CNC1A10"
Start-Process -FilePath "C:\hub4com\hub4com.exe" -ArgumentList "--bi-route=0:All --use-driver=tcp 4003 --interface=10.xxx.xxx.10 --write-limit=100000 --use-driver=serial --octs=off --baud=600 \.\CNC2A00 \.\CNC2A04 \.\CNC2A05 \.\CNC2A06 \.\CNC2A11"

But when I execute these commands both CMD windows show listening socket as (0.0.0.0) and not the IP address I specified in the 'interface option' [which I expected to show Socket(10.xxx.xxx.9:4001) and Socket(10.xxx.xxx.10:4003)] so my server is listening on both ports on both IPs.

Can you suggest where I am going wrong?