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Help me understand my network

(preface: I love my wife who, upon reading what I had originally written, suggested that I calm down and edit out some of the intro to this post)

I’m in the midst of a home networking _situation_ right now, and I’m hoping that one of you who undertands networking better than I do can help me understand what may be going on…

When we switched to cable-based Internet service a while back, I decided to go with an all-in-one router/gateway/DHCP server/cable modem – all in this tight little package. About that same time, I cancelled our phone service and switched to OOMA – nothing like having a single point of failure. However, I had never had a service failure – until yesterday.

Yesterday at around noon, our Internet service went down. I waited for a while because this was pretty common when we had DSL and it used to always come back up after a while. But the service didn’t come back up – so this morning I called Wave Broadband and they sent out a service tech. When the tech checked the ISP endpoint and my cable modem connection, everything checked out fine – but no service connection. We then reset the cable modem and noticed something interesting. I now had an Internet connection for one computer that had a wired connection to the router, but no others, and the wireless network was still completely down. The service tech said it must be a problem with my router and left.

So I did a little more digging. on running ‘ifconfig’ at the terminal, I noticed the following entry for interface ‘en0′ (which is my ethernet adapter):

inet netmask 0xffffff00 broadcast

Uhh, that’s not an allowable IP address from _my_ DHCP server (I keep things nice and local with – so where is it coming from?

Looking deeper with ‘netstat -nr’, I noticed the following

Destination Gateway     Flags Refs Use Netif Expire
default UGSc  60   0   en0

Ok, well that’s definitely not my gateway – so who’s is it – running ‘whois “n″‘ confirmed what I suspected all along – that my computer had its network configuration set through DHCP not through my DHCP server but directly by my ISP.

So the question is – why??

I called Motorola to see whether there were some firmware updates available. They told me that even if there were (there are), Motorola is not allowed to make them available as a download link because of some FCC rules stating that the ISPs must be the ones to distribute firmware updates – presumably to ensure compatibility with their networks. That said, the Motorola support folks were super-helpful – and led me to one other discovery: when I unplug the coax from the all-in-one, everything on my LAN works – my computer’s IP assigned from my DHCP server, and all my wireless devices can once again connect. However, the second I plug the coax in and the all-in-one downloads information from Wave Broadband, everything goes back to its screwed up state.

The Wave tech support people first told me that I didn’t really understand how DHCP worked and that everything was fine – and then later, after I pushed them on it, told me that there was a real problem, but that everything looked fine on the cable modem side of things and that because my device was not theirs, they refused to help me further troubleshoot the issue.

So what are some possible reasons for my network being so screwed up?? At the moment, only one computer (e.g. the one I’m writing this on) is capable of connecting to the Internet and my wireless network is down – presumably because it can’t assign IP addresses to the devices that are trying to connect to it. I’m not sure what’s going on or how to test to confirm, but I think that the configuration that my all-in-one pulled down from Wave is somehow disabling my DHCP server (and it looks like my router as well).

I don’t really have a ton of time to experiment, as I need to be able to get VOIP working again as well as ensure that my wife will have Internet access when I take my computer with me to work in the morning. However, I’m thinking that the best solution at this point is to separate my router/gateway/wireless unit from my cable modem. That’s historically been my philosophy and for whatever reason, I took a risk this time. Bleh. I’ve been looking at this unit for the router and will probably go with whatever cable modem is supported by Wave to ensure that they can’t as easily dismiss me in the future.

So, any of you with a deeper understanding of networking 1) have an idea of what could be going wrong here, and 2) how I could test for it?

Also, any general recommendations on my upcoming network setup redo?

Or, any similar horror stories you want to share to make me feel better? :)

About Howard Dierking

I like technology...a lot...
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  • Matthew Krieger

    @Doug – I’ve been using OOMA for several years and I love it. It is one of those seems-too-good-to-be-true things but it does what it says for almost no monthly cost (there still is a several $ cost due to FCC-related taxes). So pay 1 time for the box and a few bucks each month. OOMA has been very reliable.

  • howarddierking

    UPDATE: got the NetGear router hooked up and a stand-alone cable modem – everything is now working again. The cable company is even looking into refunding me for my bricked all-in-one. Thanks all for your help!

  • howarddierking

    Agreed. The problem is that the cable company seems to have also disabled my ability to turn on the router and DHCP server. My new stand-alone router should arrive today, so will be able to test that hypothesis.

  • http://www.facebook.com/andrew.steenbuck Andrew Steenbuck

    It sounds to me like your router isn’t acting as a DHCP server. That would explain why your one computer gets an IP address relative to the Gateway. The other computers cannot access the internet because they have no IP addresses. The cable co will only assign one IP address to your connection, which should typically be assigned to the WAN side of the router, and then your router will assign IP addresses internally. Not familiar with that particular model, but routers will often have a ‘DHCP Mode’ setting that will allow options such as ‘On, ‘Passthrough’, etc. It sound like yours might be set to pass through, in which case setting it to On or similar may help your situation.

  • http://blog.componentoriented.com D. Lambert

    Do you have NAPT enabled or disabled? I googled “bridge mode” and that model #, and there are all sorts of links about how to put it *into* bridge mode for people wanting to use their own routers, etc., and some of those links do imply that their cable providers are able to mess up the modem by pushing configuration files to it. If you haven’t tried calling Wave back again, that might be worth a shot, too — you might get lucky and find someone a little more helpful. It sure sounds like Wave is contributing to your problems here.

  • howarddierking

    yea – I was originally expecting to see the DHCP menu to just confirm whether or not it was setup correctly. Imagine my surprise when the entire set of sub menus under ‘basic’ had disappeared…

  • howarddierking

    Yup – the cabling is correct – in fact everything was working great for a couple of months before. So there was no change made on my end. My suspicion is that my ISP pushed an update to my Motorola and basically turned it into a really expensive bridge. I have done a factory reset – it works fine as a router when unplugged from the coax – goes back to the bridge behavior when the coax is plugged in.

  • http://www.facebook.com/mantas.audickas Mantas Audickas

    It looks like your router bridging connections. Are your cabling correct? The cable which comes from ISP should be plugged in the socket marked as “Internet”.
    If this one is correct, maybe makes sense to make hardware reset and reconfigure from scratch.

  • http://blog.componentoriented.com D. Lambert
  • Doug Wilson

    Once you get all this stuff sorted out I’d love to hear your thoughts on OOMA.

  • howarddierking

    Yes, I can still log into the Motorola admin app as admin. Unfortunately, there doesn’t seem to be any admin UI for WAN/LAN configuration – seriously, the only option is a dropdown to enable/disable NAPT. I thought that there used to be more there, but I could be remembering a former router. This is one area where Motorola looses some major points – the hardware seems solid – the admin software is TERRIBLE.

  • http://blog.componentoriented.com D. Lambert

    The fact that you’re able to connect to the Internet with that box (even under some configurations) is hopeful. Don’t lose faith just yet. I assume you’re able to log into the Motorola box as an administrator to set up configuration on that box (since it’s your box)?

    Somewhere in that interface (without actually trying to scare up a user manual for that device), you should see references to WAN setup and LAN setup. In your case, “WAN” will be the cable modem part of the device, and “LAN” will be all of the devices in your home. On the WAN side, the Motorola is a DHCP client — it’ll get its configuration (on that side only) from the cable company. On the LAN side, the Motorola is a DHCP server, so this is where you set up how you want your home network to look.

    You’ll probably also see an option in that UI somewhere to do some simple IP testing (ping) right from the UI — this will help you verify that the stuff facing the cable company is working all right.

    If you can verify that much, everything else should be a matter of configuring the Motorola, which you should have full access to. Does that sound about right so far?

  • howarddierking

    without drawing a diagram, the topology looks like this: coax comes into my Motorola box. The Motorola box includes a cable modem, router, DHCP server, and WAP. Hence, everything on my LAN connects to the Motorola box (either wired or wireless). One mistake that I think I made here was buying this gear myself – it’s not the hardware that Wave issues – and as a result, they are basically telling me that because everything looks fine on their end, it’s not their problem.

    I think that the next thing for me to do is get a bit more control over things by separating my LAN infrastructure from the modem (WAN) by having them as different bits of hardware – as you mentioned, this also gives me the ability to do things like run a guest network.

  • howarddierking

    right – what seems to be happening in my current situation is that (because it’s an all-in-one unit) the ISP configuration has effectively disabled my router so that there is no separation between WAN/LAN – hence, my DHCP server (also included in my motorola box) is not assigning IP addresses when connected to the ISP. The way that I verified is by disconnecting/connecting my motorola box to the cable. When disconnected, my SSID is able to accept and issue addresses to wireless clients (all in the 192.168 address range) – when connected, only the first wired port gets an IP and it’s in the 66.235 range. No other IPs get issued to any devices on my network.

  • http://www.facebook.com/people/Jeffrey-Bakke/100001722111778 Jeffrey Bakke

    This is my bet. Your all in one unit is configured as a ‘bridge’ instead of a ‘router/firewall’. So you’re getting a DHCP from the ISP instead from the device itself. You’ll only get 1 IP DHCP address because of this. You can easily solve it throwing another cheap router connected to it via the LAN port. But obviously you don’t want that, so you’ll have to fight your provider. Sorry.

  • http://blog.componentoriented.com D. Lambert

    I’m not sure it’s really a matter of “illegal” as it is about how devices obtain their configuration. All the basic IP settings are either static or dynamic (DHCP). It’s appropriate and normal for your devices (as well as the modem itself) to be dynamically configured via DHCP. The modem should also have a router that recognizes a “WAN” side and a “LAN” side, and should also have a DHCP server that assigns addresses for LAN clients. I believe that is that server.

    When you mention *your* DHCP server (, I’m really not clear what device you’re talking about, nor how you know how this address is set up, so a little extra illumination on that front might be helpful, too.

  • http://blog.componentoriented.com D. Lambert

    It might be helpful to do a little diagram to help us out here. You’ve got a cable modem that I believe is also your router / firewall. Based on the Motorola link, it looks like it can also be a wireless access point, but I can’t tell for sure if you’re using that functionality.

    I think the bottom line is that if you’re really doing the all-in-one (including wireless), then all of your networking problems are Wave’s problems — that’s the value proposition for getting the all-in-one device and giving them control over all that setup. All of your networked devices should connect via DHCP and wind up with whatever IP configuration they obtain from the DHCP server in that Motorola unit. To be clear, that unit has a WAN side and a LAN side, and if your devices are obtaining an IP connection via DHCP, it should be happening via that box — not via a DHCP server outside your home, if that’s what you’re thinking.

    If you want a little more control over your home network, that might be a good thing, as long as you know where your stuff ends and their stuff begins. Personally, when WOW showed up at my house with their all-in-one box (I forget the brand), I had them turn off wireless and everything else in that box except for ethernet, and I connected my Cisco RVS4000 to it. Everything else in my house connects either to that or my Cisco WAP4410N wireless access point. That might be too many devices for some people, but I like the control I’ve got, including the fact that the router and WAP can work together to put guest wireless traffic on a V-LAN that can’t touch my “regular” network. This became a selling point for me as soon as my teenage son invited his friends over and all of them pulled out their laptops and wanted wireless access. They’re all great kids, but I feel better knowing that whatever they’ve got running on their laptops stays the h*ll off of my network.

  • howarddierking

    (for my ISP anyway) it doesn’t matter whether it’s their equipment or yours – they have perms to push updates (including config) to the modem. I think the problem in my case is that my modem is the same hardware as my router.

  • howarddierking

    that’s what it looks like to me as well – the concerning thing is that in the router configuration app, it says that NAPT is enabled – even though it’s not behaving that way…

  • howarddierking

    yes, the ISP has access to reconfigure the cable modem. In my case, because the cable modem is the same device as the router, my suspicion is that my ISP forced my router into bridge mode, which would explain why their DHCP server was configuring my actual computers’ network configuration. My next step plan is to run a separate router from the modem – I’m pretty sure that while my ISP can reconfigure the cable modem all they want, it’s illegal for them to change any state outside of that modem.

  • Bob Archer

    This could only happen if the ISP is modifying your modem settings. Since it isn’t ISP provided equipment they shouldn’t be doing that.

  • Bob Archer

    Hard to do this over comments. I recently had to troubleshoot some issues.

    (well I did pass the TCP/IP test when I got my CNE)

    When you say “no internet connection” are you saying there was no connectivity at all? You couldn’t ping external sites? Did you still see all your local pcs on the network.

    Generally, as I’m sure you know there is a “lan” connection on the router and you set up the router to use your ISPs DHCP to get it’s external IP. (I’m not 100% sure how this works when the cable modem is internal but I expect it is the same). Then the NAT service will route everything through the router.

    The routers DHCP service will generally send internal IPs to the devices connected to it and that will include the gateway address which should be the routers internal IP.

    What I don’t understand is how this could have changed from one day to the next. Does your ISP have access to change your modem/routers setup?

    You think you may want to try is to just hard code IPs and DNS on your devices. It isn’t perfect but may be a good work around. Specify your router as the default gateway and you can use google DNS / as the DNS server.

    Other than that, since everything was working you might want to do a factor reset on your modem/router and reset it up. It sounds like something change.

    It doesn’t make sense why moto wouldn’t provide firmware updates considering you own the device.

    I’d be happy to help via phone if you want.

    (BTW: My horror story is too long to tell here.. but it hinged on the DNS server in the Verizon router just going to lunch every now and then so all the PCs got DNS errors.)


  • sodablue

    Sounds like your cable modem is working as a cable modem and not a router.

    I suspect you could use your existing cable modem. As the wifi isn’t working and it’s in bridge mode, if you can keep it that way… just add a router behind it. I like the Netgear stuff. I have a WNDR3400 which has been pretty solid the past 3 years but the 3700 is better built.

    I occasionally have to power cycle everything off and then on again. I sometimes have problems where wifi is no longer allowing connections and that’s the only solution. It seems to be the router is handing out the same IP to two devices and that’s not good.

  • wwb_99

    +1, Definitely sounds like the ISP is forcing bridged mode. Sounds like the ISP did a modem firmware update for others moto devices and changed settings on yours. You should be able to login to the device and disable this.

  • http://twitter.com/schakko Schakko

    We have the same situation here in Germany with one of the biggest providers Kabel Deutschland. They although provides the IP addresses with DHCP, at least in my region. The complete TV/IP cable infrastructure sucks as every cable modem (some Motorola too) sees every other cable modem in the /24 subnet. This means, you can access the modems or connected PCs via SMB which are in the same subnet as yours if they are not behind a router/firewall.

    Whatever. It seems that your cable modem does not longer act as a router but as a bridge. The manual (http://www.motorola.com/on/demandware.static/Sites-Site/Sites-Motorola_US-Library/default/v1335985434876/Promotion/cross-sell/cable-modem/SURFboard_SBG6580_UserGuide.pdf?version=1,336,493,317,000) is not very helpful. Can you see any options which enables/disables a bridging mode inside the GUI?

    Bridging means that every physical connected port acts as one big network. Every Ethernet broadcast is sent to any physical port. Your PC (which receives the DHCP address) sends a broadcast via Ethernet/IP/UDP/DHCP and the cable modem broadcasts it to every connected port, including the port connected to your provider. The provider receives the DHCP requests, answers it, sends it back to the network and your cable modem broadcasts it to your network.

    Often the bridging mode functionality is only bound on Ethernet port 1. Does your computer receives an IP address from your providers DHCP if you connect it to port 2?

    As you already mentioned I suggest the following setup: [provider] –TV cable– [Motorola cable modem] — Port 1 — [new WLAN router] — your internal LAN.

    I could be totally wrong with this post but that seems to be the most obvious reason.

  • howarddierking

    oh wow – I didn’t know that some ISPs did that. If mine is, then they just started doing it yesterday and failed to mention it…

  • pontios1983

    Optus here in Australia use to (and probably still does) disable DHCP on the cable modems. So that could quite possibly be the issue.