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Saturday, 1 January 2011

Beware the Fritz!Box 7390's 'green' LAN mode

I've just been testing a D-Link smart switch, and due to limited space on my desk had to stick this in front of my cheapo Belkin 8-port Gigabit switch (F5D5141-8v3). This meant the link status LEDs were hidden from view. Having finished the review and packed up the D-Link, I noticed that the uplink to the Fritz!Box 7390 (which I have on long-term loan) was only running at 100Mbps. Puzzled, I tried connecting the PC direct to the Fritz!Box, with the same result - all the LAN ports were running at this lower speed.

Thinking it might be the new firmware upgrade, I tried to think of something that might have changed. For some reason I thought of the 'green' LAN feature, so I checked it and noted that the ports were set to automatic 'green' mode. I changed this to 'always on' and hey presto, the link speed changed to 1Gbps. I wasn't sure why, though, but checking the help file revealed all - the 'green' mode just reduces the port's speed to 100Mbps when a device is connected. Obviously, this does help the Fritz!Box save power, but for some reason I thought that it did other clever things like reducing signal strength for short cables, like some other networking kit I've seen (D-Link's Green Ethernet technology is an example). It does turn off power to unused ports, however.

So be careful activating the green function if you need full-speed LAN connections - one of the few annoying things about the Fritz!Box is the lack of visible port status information - and even in the web interface there's no indication of the active link speeds. The safest compromise between speed and power consumption is to set all ports to the 'Identify Automatically (Power Mode)' setting - this runs ports at the full 1Gbps, but turns them off when there's no cable connected.

Don't do this if you want a full-speed LAN

UPDATE 31/1/2011: I've corrected parts of this article, as the Fritz!Box 7390 does turn off power to LAN ports with no device connected, unless the 'Always Enabled' setting is used.

 UPATE 19/9/2012: The latest FritzOS 5 firmware adds the details of port speeds to the energy settings screen shown above.
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17 comments:

  1. silne3 August 2011 at 22:10

    THANK YOU THANK YOU THANK YOU!!! Although mine were in the mode suggested already, and I had to switch them to "automatically identify (power mode)" to get gigabit ethernet happening here. I wish I'd known this last night when it was driving me crazy!

    ReplyDelete
  2. Anonymous18 October 2011 at 06:01

    +1 million

    Many thanks!

    ReplyDelete
  3. Anonymous12 December 2011 at 21:47

    Oh man, I cannot believe I missed that. I was completely on the wrong foot by the 1Gbit connection on port A. As my server was in that port I never disconnected it and only used the other ports for my other computers.
    I was convinced the problem was in the linux forcedeth driver, but then another (windows computer) wouldn't connect at 1Gb either. Both used the same Realtek chip so then I thought there was a problem with that. Caused me sooo much frustration.....
    THANK YOU THANK YOU THANK YOU !!!

    ReplyDelete
  4. Kelvyn Taylor23 June 2012 at 12:07

    @ Craig Hi there, and thanks for dropping by. Which device is saying that the link is 100Mbps, that is, how do you know? If it is shown on the HTPC it might be that the network adapter isn't auto-negotiating the link speed correctly (but then the switch would tell you that). Also, which Fritzbox model?

    ReplyDelete
  5. Anonymous10 April 2013 at 12:26

    THANK YOU THANK YOU THANK YOU!!!
    2 days I m looking for this problem !

    ReplyDelete
  6. Anonymous24 November 2013 at 11:51

    Thanks a lot! Solved my problem immediately!

    ReplyDelete
  7. condamned1821 April 2014 at 18:45

    I don't have the Settings option on the energy monitor panel

    ReplyDelete
    Replies
    1. Anonymous10 August 2014 at 13:00

      Same here, just got the lattest Firmware too 06.06

      Delete
    2. Anonymous10 July 2015 at 14:52

      Same here. No option button...

      Delete
  8. Anonymous30 April 2014 at 12:14

    Thanks man was about top return the box

    ReplyDelete
  9. Anonymous27 July 2014 at 07:29

    Users may be interested to know that the location for these settings has changed in a more recent firmware update.
    The 'Green Mode' settings can be found in;

    Home Network > Network > Network Settings tab

    Don't forget to hit 'Apply'!

    ReplyDelete
    Replies
    1. Kelvyn Taylor27 July 2014 at 14:00

      Thanks for that! I'd spotted that, but didn't think to update this :-)

      Delete
  10. Anonymous18 May 2015 at 14:06

    Many thanks to all. I have the 7360 and I can only have 2 power and 2 green, still better than the 1 power I have been struggling with. I will try the ISP for an upgraded router. Again thanks

    ReplyDelete
  11. Anonymous8 January 2016 at 21:55

    If you hit Apply does the FritzBox reboot? I'm backing up a large file and it has 16 hours to go. :-(

    If I hit Apply will the port speed automagically increase or will that interrupt my backup?

    ReplyDelete
  12. Anonymous9 January 2016 at 10:11

    You wrote: "the 'green' mode just reduces the port's speed to 100Mbps when a device is connected. Obviously, this does help the Fritz!Box save power".

    >>> I don't understand how port speed can save power?

    ReplyDelete
    Replies
    1. Kelvyn Taylor13 January 2016 at 21:03

      Gigabit Ethernet needs more processing power than 100Mbps Ethernet, which in turn uses more electrical power - obviously not a lot, but it does. That's why they call the slower mode 'Green Mode'.

      Delete
  13. Anonymous10 July 2017 at 12:29

    With the actual Firmware 06.84.xxx you can see the 4 ports as either 1 Gbit/s-POWER-Mode or 100 Mbit/s-GREEN-Mode. You can switch every port individually.

    ReplyDelete

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