When your home's Internet goes down, here's a cellular work-around

Posted by Paul Braren on Jul 15 2012 (updated on Oct 29 2012) in
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  • It began with a sketch after a storm in 2011:


    Hopefully this Visio version is a bit easier to interpret:


    It all started at 11am today, with me noticing all my home's devices had gone offline. No clouds available. Without the usual green blinky lights on my DOCSIS 3 cablemodem:


    and the loss of TV signal itself, it was pretty obvious what was wrong. Cable TV and Internet were down.

    I called Cox up at 11:10am, with no outages were yet reported in my area (and no status site to visit from my smartphone). The support representative could see my modem was entirely offline. He then looked at my town's status again 2 minutes later, and indeed, my entire "node" had now been spotted as offline, about 500 residences in all.

    To get the family through this 3.5 hour weekend outage, it was time for the "known-good" workaround, that I've implemented before, including during these near-disasters:

    • August 2011's Tropical Storm Irene in August 2011, taking out power for days (which kept a lot of folks from getting to VMworld)
    • October 2011's nor'easter, with extremely sticky and heavy snow that took out power and cable all over southern New England for nearly a week. Getting on a borrowed generator to save the groceries and Internet were first priority. Being able to share out 4G WiFi with my temporary house guests beyond 5 devices wasn't just convenience, it was for family safety, and to be able to do our jobs. Having 2 solid Ooma VOIP phone lines working was very helpful as well.

    Here's my home "disaster recovery" procedure

    easily adaptable to your situation, and takes only a couple of minutes to set up, particularly once it's been done before:

    1. Remove the network cable that plugs into the "Internet" port of router (that leads to the cablemodem)
    2. Plug a network cable into that "Internet" port on the router, with the other end plugged into a laptop (in my case, an ancient ThinkPad T30 32 bit Windows 7 laptop)
    3. Power up the Verizon MiFi 4510, be sure green indicator shows on 4G
      (if you have a cell phone with tethering data plan, you can share that connection instead, but it's your responsibility to follow your EULAs)
    4. Power up the laptop, and be sure its wireless adapter is associated with the MiFi's WiFi
    5. Right click on the laptop's wireless network connection, choose Properties, then choose Sharing (see screenshots below). This turns the laptop into my temporary router, granting a DHCP IP address just to my home's router. It uses the "Internet Connection Sharing functionality" built into Windows.

    Once power is restored:

    1. On your temporary laptop that acted as a router, turn Sharing back off (to avoid possible DHCP issues)
    2. Unplug the cable from the "Internet" port of the router, and plug the original cable back in (that leads to the cablemodem)

    That's it! Your cablemodem should grant your router a new DHCP lease, and your regular surfing through your regular ISP should be back to normal.

    The benefits of this overall approach include:

    • the existing router automatically gets a new DHCP IP address from this T30 laptop within seconds, which then blesses with 4G Internet all devices already associated with it, wired and WiFi connected, no reconfiguration of all the household's devices necessary
    • because the devices aren't associated with the MiFi directly, it works around the 4510L's 5 concurrent user limitation
    • leave a TV on with the volume up, showing a no signal warning but tuned to an actual station.
    • when the TV channels come back up, you are then automatically notified by the noise from the TV, prompting you to check on the cablemodem lights as well

    The drawbacks of this approach:

    • warning, keep a close eye on that cellular data usage, since you can exceed your monthly 5GB cap in as little as 6 hours!
    • not as automatic is a router with built-in USB ports for automatic cut-over to backup internet connections, such as the now obsolete CradlePoint MBR1000 that I've used quite a bit in the past:
    • be sure you turn off Sharing when you're done, otherwise, your laptop's wired connection will become a DHCP server and you don't usually want that!

    Since this particular approach involves moving a cable, the IT geek in your family needs to be home when bad stuff goes down, or at least available to talk a family member through the above procedure remotely.




    Verizon 4G (even with ancient laptop acting as router, latency still quite low)


    Update Oct 29 2012:

    Here's a video of the sharing process, using an iPhone 5 and the "Personal Hotspot" function with USB cabled to a Windows 8 laptop, with the laptop sharing over an Ethernet cable to to router: