On my Netgear router (WNR3500L) amber means 10/100 mb/s and green means 1000 mb/s Ethernet speeds.
The OBi runs at 10 mb/s by default, but can be switched to 100 mb/s using the following procedure:
1. Dial *** 0
2. Enter option 27 and press #
3. Press 1 to set a new value
4. Enter a value of 1 and press #
5. Press 1 to confirm/save
6. Hang up
7. Wait for the OBi to reboot