I found the problem.
The API was setup in IIS with both an IP Address and a Host Name (abc.def.com). The Android device could not use the Host Name as it had no way of resolving the IP address from the Host Name. If a Host Name exists, it appears that IIS forces you to use it and IIS will not recognize the IP address.
Once I removed the Host Name from the Bindings screen for the API in IIS, I was able to use the IP address to successfully send and receive REST requests from the Android device.
I have a Windows 10 Pro 64bit notebook with a website hosted by IIS. The notebook PC is not connected to any network and does not have internet access. I am using a product from the Microsoft Store called WiFi Direct Access Point (WDAP) to create a network that an Android device can use to access the PC via a wireless connection.
WDAP has assigned the notebook PC the IP address of 192.168.137.1 and the Android device connects and is assigned 192.168.137.### (### changes each time I connect).
The website I want to access with the mobile device can be accessed on the PC, but it is not being recognized on the mobile device. The mobile device browser (Chrome) is reporting that the website is not accessible. I have tried using the PC's name and the IP Address of the PC in the URL when accessing the website.
Any suggestions on how to accomplish this task would be greatly appreciated.