Connection Error "-4009 - Failed to connect SLD, make sure SLD server is correct and available"

[NB: Error code "-226" is also related to this error (SAP 9.2 Version)]

What is the reason for this error?

You DI-API installation have a misconfiguration in it's 'b1-local-machine.xml' file on the machine that runs the Server-component or you have not opened ports in the firewall.

How to fix it?

First in the firewall that host the 'SAP Server Tools' open inbound firewall ports 30000, 30010 and 40000 [Boyum cannot help with firewall related issues beyond this text]

Second; Log into the System Landscape Directory (SLD) and once logged in, notice the URL (Example: https://myServer:40000/ControlCenter/). Now go to folder 'C:\\Program Files (x86)\\SAP\\SAP Business One DI API\\Conf' and edit 'b1-local-machine.xml' to have the same server and port as the previous noticed URL (Example: https://myServer:40000) [NB: SLD in some setups use port 40000 instead of 30010]

Videos how to fix (Part 1 and 2):