Information
Time-to-live (TTL) is a value in an IP packet that tells a network router whether or not the packet has been in the network too long and should be discarded. Select this option to decrease the TTL value for packets that have been forwarded and therefore have already been in the network for some time.
Solution
Navigate to Firewall Settings->Advanced->Detection Prevention and check off 'Decrement IP TTL for forwarded traffic'.