Hello
1.Try to locate the domain ID from the sylink.xml file on the client not communicating located at:
C:\program files\symantec\symantecendpoint protection
Right click on the file, and open with notepad.
Locate the domain ID in the file, copy and paste it on the notepad.
2. Browse to SEPM select Admin option on the far left.
3. Select add domain, new window pops-up. Give this a new name, and select the advanced radio button.
4. Once you click on Advanced, it will ask for the Domain ID.
5. Copy the Domain Id that was pasted on the notepad in step1. here.
6. Click "Default" domain, and under tasks select disable. SEPM logs off.
7. You will notice the clients communicating with the new SEPM, once that starts to happen, delete the "Default" Domain ID.
Please note: The clients where you already replaced sylink.xml, will not be able to communicate after performing these steps, please replace the sylink later onne rest of the clients are communicating fine.