Sounds like a good question to ask over in the Report and Issue section where this can be evaluated as a possible bug. (The Filemaker techs will then look at it and respond back whether this is or is not "by design".)
Thanks PMJ. That said, I'm new to using this forum - should I simply repost it there or can it be moved?
I would if I could. I find that I've recently gained the ability to move posts to certain other "hives" as they call these topic areas, but Report an Issue is not on the list--probably due to the detailed report form you are asked to fill out over there that isn't used over here.
I am having the same problem, and saw the Issue Report on this - http://forums.filemaker.com/posts/7845748fe6. The answer on the Issue Report from Tech Support was they see the DNS path, not the IP address (which is not what we are seeing). I called Tech Support and spoke with Andrea - she created a Snapshot Link and opened it in Text Edit. She saw what we see - the IP address.
Andrea's workaround was to open your file (where you are creating the Snapshot Link) using the external IP address (instead of the internal IP address), and then create the Snapshot Link. It will then contain the External IP address. This is not much of a workaround, because your internal users are then not using the LAN.
FileMaker needs to give you an option when you create the Snapshot Link to use a different IP address. It could default to the internal IP address, but allow you to substitute the external one. Since there also is a Script step for the Snapshot Link, they should allow you to change the IP address there as well.