FRITZ!Box 3390 Service - Knowledge Base
Supported throughput when using FRITZ!Box with an external modem or router (e.g. cable modem)
Not only can the FRITZ!Box use its internal DSL modem to establish internet connections, it can also do so using an additional DSL, fiber optic or cable modem. In addition, the FRITZ!Box can use an existing internet connection in the network, for example if the internet service provider requires you to use a special network termination device (IAD, Integrated Access Device).
In some cases these operating modes require special protocol stacks and packet encapsulation as well as additional security mechanisms such as NAT, PPP, PPPoE, VLAN, "Stateful Packet Inspection" firewall, port forwarding, traffic shaping etc.. This may reduce the maximum possible transmission rate for the "LAN 1" port of up to 1000 Mbit/s to slightly less than 200 Mbit/s.
Important:The internet access speeds that can actually be achieved depend on all of the components involved in transmitting data. Besides the FRITZ!Box, these include the network device and its network adapter, the upstream modem or router, the internet connection, the internet service provider and the remote site in the internet.
There are no standardized methods of measurement, and the results of so-called "speed tests" vary greatly due to numerous factors influencing the results.