Hi,
in the sylink.log you can read step by step the details about the manager-client communication, they are split in less than 10 check points.
First of all the client tries to connect to the manager for the registration and the authentication and to get the index.xml where the manager publishes the index of the latest updates.
The client compares the index.xml with its own list of current contents and a result code is visible to report what contents are needed, what of them are already up to date and what of them have to be ignored (for example the 64-bit contents are ignored in a 32-bit client).
The client starts to download the required new contents.
This communication is based on the http protocol and managed by the web site installed in IIS in the management server. For this reason every failure is a standard IIS error code and requires a standard IIS troubleshooting:
support.microsoft.com.
I don't know an official document about the sylink.log.
Regards