[lukewest]

I am using the following systems/settings:

1) An iPhone 7 plus with iOS 10.2, and
2) Calibre Companion IOS installed
3) App connection to Dropbox (confirmed from within Dropbox > Security)
4) Calibre 2.74.0 on my MacBook Pro, running Sierra
5) The Calibre library is on my personal Dropbox, as "Calibre Library" in the root filesystem.
6) In this folder are the metadata.db and metadata_db_prefs_backup.json (confirmed from the command line and from within the web interface for Dropbox) [Separate thread]

Nothing works for me.

(adding in some more information)

The Mac and the iPhone are on the same home network.
There are no firewalls blocking internal traffic

Subnet: 10.202.1/24

Content server:
I started content server on 10.202.1.44:8080
I open this in a browser on the Mac and get the Calibre interface.
I open this on a browser on my iPhone and get the Calibre interface
I try to open the Calibre Companion and get a failure

Wireless server:
I started wireless server on 10.202.1.44:9090
I open this in a browser on the Mac and get an invalid response (ERR_INVALID_HTTP_RESPONSE).
I try to open the Calibre Companion and get a failure

So far I have bought an app an nothing works :-(

Any help would be appreciated...!