IndyMike

Hey bmarsh,
I'm a windows user that hasn't played with Linux for years.  My Win10 system does regularly "forget" the ISY location.  I normally "Load" from a saved file, or "Add" the location manually.
Assuming you know the local IP address for the ISY, you can simply "Add" as follows as shown below (use your own IP address of course).  Note that the "HTTP://" is mandatory.  If you want to add with security, simply use "HTTPS://"
If this works, save yourself some headaches in the future by using the "Save" button to save the file to a convenient location.  You can then "Load" at some point in the future when the loader forgets the settings.