Port conflict after upgrading Sametime to 7.0.2

I'm looking at an iSeries running V5R3 that hosts three Domino servers in a
single partition: One each for QuickPlace, Sametime, and Domino. Until
this weekend, all three Domino servers were running Domino 6.5.4 and have
now been updated to Domino 7.0.2. I'm really thrilled with how smoothly
the transition was, to be honest, but I have one puzzle.

In February, we configured the second Ethernet card in the iSeries to
attach to a different network than the first card. We wanted the Domino
and Sametime servers to be directly accessible on this second network
without the additional routing that was necessary with our previous
configuration. I set up the Domino and Sametime servers with IP addresses
on the second network and we had it working successfully for a few days
before an issue came up that caused us to put the project on hold. I say
this mostly to illustrate the dual-address servers were both working. Even
after the project was put on hold, I left the second IP address on each
server with the hope that the project would come back to life and we could
finish it out.

However, after this weekend's update to 7.0.2, the Sametime server was
unavailable from any Notes clients. The log was showing a constant stream
of "Error on Listen function: The requested TCP/IP port is in use on this
system." and "Listener task for port TCPIPNTW is suspending for 20 seconds
due to listen errors". Since TCPIPNTW was the port I created for the
second connection and we are not using it, I shut down the port. After
that, everything's running great, but I have two questions:

First, I shut down the port with "stop port tcpipntw" at the console. Is
this a permanent change, or is it going to reset to use that port when the
server is next restarted?

Second and more importantly, why did this port suddenly become a conflict
after the upgrade when there'd been no issue for several months?

Thanks,
Patrick