What is consider decent latency / RTT for WAN / LAN?

The general question is hard to answer since it depends on the application and on the technology being used. In your specific example, what is the topology? read more

There is no single answer to this question. Depending on what the WAN/LAN link is being used for, different RTT's will be perceived as acceptable or not by the users. The key word here is"Perceived". read more

There are two normal factors that significantly influence the latency of a consumer device (like a cable modem, dsl modem or dial-up modem). The latency of the connecting device. For a cable modem, this can normally be between 5 and 40 ms. read more