Just to let all know, especially Ducky, that I now have both my systems running on Dyna and drafting each other from both. I have had no issues at all or drops when drafting my other system, with my son at the helm. If he joins any house it would be his choice as I have not told him to join mine(yet).
Suggestion Duck it is most likely the router or whatever you are using to split the signal to 2 IPs either has a firewall or some sort of protection to negate your cross connections. Could also be one of your 2 systems may have the LAN part turned off or blocked as well.
I will be away for a few days but perhaps we can talk again of this issue with your 2 systems when I get back next week(or sometime before KCW).