App mon does not have a network latency measure per se as the agents reside on the JVM looking at transactions. For network related metrics, DCRUM, another product from Dynatrace would serve the purpose as the data is taken off the wire looking at packet information.
From Application Monitoring the closest you can see time related to the network is by looking at the Inter tier time, in the Transaction flow, between your different tiers. Inter tier time occurs between two agents.This time usually comes from transactions that pass through a tier. This may be network latency or other network related problems, or other tiers that are not instrumented.
Hope this helps.