By the way, your property values are both null.
mDNS is not available on the official esp8266 port (which I am running).
I have changed “href” to use the “links” array instead.
FYI, the hardware I am using is here: https://www.electrodragon.com/product/wifi-iot-relay-board-based-esp8266/ which is using esp-12 and IO12 and IO13 for the 2 on-board relays, and IO14 for the on-board DHTXX which is useless because of the heating effect of the on-board power supply 
By the way, your property values are both
null.
Just fixed that
Another question, if devices are listed in the “+ add Thing” page that are only discovered by dns, why is it that one of my things is automatically listed and can be added from this page ?
The other, first device in the http://host/ JSON array is not shown and has to be added manually ?
You probably have one of the two configured in the add-on settings, i.e. in Settings -> Add-ons, then click Configure on the “Web Thing” add-on. That’s the only way they would show up without mDNS.
Things still appear to be working properly for me with your changes.
I misunderstood the purpose of the URLS added to “Configure thing-url-adapter” setup page.
I assumed that these were the server host addresses, and that the module would make a call to thee root (/) of each URL listed there to get a list of things that are hosted on that host.
So in the urls field I added the host IP address: http://192.168.0.186/ and by doing this, when you click the + on the tings page to discover new things, the module does query this page and returns the last item found in the JSON array for http://192.168.0.186/
I then added this item by clicking the save button, but as the other thing was not discovered I added that manually.
Then when I look at the server logs, the web things module does not poll both devices, but polls one device twice.
mDNS is not well supported on the official ports and querying the root of the server for a list of things on that server seems a much easier thing to do
I actually can’t even reproduce that. If I put in the base URL to a server with multiple things (in the add-on config), they’re both still discovered and polled properly.
Regardless, it sounds like you have things working properly now.