To prevent Symantec Endpoint blocking access to our Endpoints you may need to add need to add out domains as Trusted Destinations. Following the below steps:

Steps:

1. Launch Symantec Web Security Service
2. Navigate to Policies  
3. Select Content Filtering
4. Locate your Trusted Destinations and click to open
5. At the top of the new window Click New  
6. From the drop down select Domain/URL
7. Enter the following Domains, clicking Save after each one(Repeat steps 5-7 for each domain)
8. Add Comments if required
   
   

9. Save the Rule
10. If not already done, at the top toggle SSL interception to Enabled
11. Click Activate