If you need to switch sylink.xml file and get the communication back between Symantec Endpoint Protection Manager (SEPM) and client, follow these steps:

1- Copy sylink.xml file to the client you want to restore communication;

2 - Run the SylinkDrop Application located in the path:

C:\Programs Files\Symantec\Symantec Endpoint Protection\12.1.xxxx.xxx\bin\SylinkDrop.exe

NOTE: In case of password protect to stop SEP by Policy is set it up, SMC services should be stopped first and then use Sylinkdrop.