by Archie500 @ instructables.com:
In a very brief summary it works as follows: The Raspberry Pi uses SNMP (Simple Network Management Protocol) to get the WAN data rates from the router and then displays these graphically on the OLED screen.
The Raspberry Pi was already set up as our media player and is next to the television. The OLED display was inexpensive and can be bought from a number of places including eBay.
Raspberry Pi OLED Internet Bandwidth Display – [Link]