These may help
Neocode software offers free Filemaker Database Hosting
Thank you for your post.
It sounds like you have everything set up correctly.
The external user would enter the IP Address of the machine hosting the file. Therefore, make sure the hosted machine has a static IP address. Otherwise, the external user would not be able to access the file.
The default for Instant Web Publishing is port 80. This port is used by a number of browsers to access the internet. Some users have reported a conflict with this port, so FileMaker, Inc. has registered port 591 to be used only with FileMaker Pro. That is, no other application will use this port. Therefore, you may want to try port 591, and then have the external user enter the URL:
If this doesn't work, then you probably don't have a static IP address. I would check with your Internet Service Provider to see about obtaining a static IP address, or use one of the many hosting services available, including those posted by "davidanders" (Thank you!).