To modify the firewall policy
In Symantec Endpoint Protection Manager, on the Policies page, under View Policies, click Firewall.
Find the policy that is associated with the group that contains the DHCP server. Right-click this policy and click Edit.
Click Rules > Add Blank Rule.
In the Name column, give the rule a name such as "Allow DHCP server."
In the Service column, right-click the new rule and select Edit.
Check DHCP Server, and click OK.
Move the new rule above any other rules that would otherwise block DHCP server traffic.
Click OK to apply the policy.