[EddieJones]

You should be fine using either port for internet with current v1.4.1 software if you are using the internal S6 DHCP Server.
We discovered a rather obvious issue with all EUCON surface setups that used 2 ports on the Workstations a few months back. With Artist it wasn't so much of a problem because most people have the surface on the same network as the internet but with pro consoles where the surface should always be on a separate network it caused lots of issues.
The issue is having a DHCP Server or Router on each network gave the Workstation 2 Default Routes to get to the Internet/WAN/Intranet etc. So the Workstation didn't know which was the right one to use. The solution for S6 was to disable the Default Route in the S6's DHCP Server leaving the real Internet network to supply the correct Default Route to the Workstation. On S5 Hybrid we were able to set static addresses on the Workstations leaving the Default Route blank.

Hope this helps...