If the Certificate on your DLP Network Controller has expired, all Network appliances will appear down, yet Events will continue to appear in the Enterprise Manager.
System will also be unable to add additional NW devices or push Configuration changes or Policy Updates to NW Devices

Here are the steps to renew this certificate.

Step 1: 
 
If DLP 9.5 or greater  DO NOT USE THIS PROCEDURE, 
Go to the RSA DLP 9.5 Maintenance Guide: https://knowledge.rsasecurity.com/docs/rsa_edp/dlp_95/RSA%20DLP%209.5%20Maintenance%20Guide.pdf
Then use the procedure listed on page 76 of the RSA DLP 9.5 Maintenance Guide

If DLP 9.0, skip to Step 2
 
If DLP 8.x continue.
Make a back up copy of the original file initssl.sh which is located at /opt/tablus/bin/initssl.sh
Copy the 9.0 initssl.sh script to /opt/tablus/bin directory on the Network Controller
The 9.0 script is uploaded to the sftp site:
https://sftp.rsa.com/human.aspx?Username=support&password=Password1&arg01=857699950&arg12=downloaddirect&transaction=signon&quiet=true

Step 2: Confirm time sync
Check the time on the Enterprise Manager host 
Check the time on the Network Controller host
Confirm that these times are in sync
 
Step 3: Renew the certificate
Log into the DLP Network Controller as the Tablus user. 
From the Tabmenu 
Stop the DLP Network Controller services
Exit to shell
Navigate to directory: /home/tablus
Run the command:  /opt/tablus/bin/initssl.sh
If the command fails see note below on file owner / permissions   
 
Step 4:  Verify
Run the command below to confirm that the certificate has been updated. 
Navigate to the directory: /usr/java/default/bin/
Run the command: 
./keytool -list -v -keystore /opt/tablus/config/keystore -storepass tablus -alias jetty
Note: there are dashes in the command above that may not be displayed properly by some versions of Internet Explorer
 
Step 5:
Type tabmenu
Restart services on Network Controller
Log on to the Enterprise Manager host 
Confirm that Network appliances all appear up in the EM user interface

chown tablus:tablus initssl.sh

chmod +x initssl.sh

If the script fails with a message 'bad interpreter', the file may have been converted to Windows format before being loaded on the Network Controller. 

In this case you will need to change the file type back to linux by issuing the following command: 

dos2unix initssl.sh