Internet Provider is Blaming my Router

Discussion in 'Mac OS X Server, Xserve, and Networking' started by cwazytech, Mar 8, 2016.

  1. cwazytech macrumors 6502

    Joined:
    Jan 7, 2009
    Location:
    Colorado
    #1
    For one week now I have been successfully connected to the Internet using my Time Capsule + my Xfinity supplied modem/router. When it was hooked up, I told the service guy that I didn't want to use the router function on the supplied modem; that I wanted to use my Time Capsule instead. He told me that I could do this if I put the xfinity router in Bridge mode. Done and done. After one week of flawless service, all of a sudden I lost Internet. The Airport utility suggested that my internet connection was lost and my time capsule was fine. I called xfinity, multiple times, and after many setting changes and restoring the Time Capsule to factory settings it looks like the only way I can get Internet through my time capsule is to leave bridge mode "off" on the xfinity supplied modem/router. Now I'm stuck with a "Double NAT" error that I'm forced to ignore until I can find a better solution. Thoughts?
     
  2. LiveM macrumors 6502a

    LiveM

    Joined:
    Oct 30, 2015
  3. DJLC macrumors 6502a

    DJLC

    Joined:
    Jul 17, 2005
    Location:
    Mooresville, NC
    #3
    I'd look at swapping the unit they provided for a standard cable modem. Often you can either request that from the cable provider or, if you're so inclined, buy your own.

    I have had many issues in the past using a router with a modem/router combo provided by an ISP. Swapping their unit with a regular old modem usually solves all issues.

    Or, as @LiveM said, give up and put the TC in bridge mode, allowing the Xfinity box to handle the routing.
     
  4. monokakata macrumors 68000

    monokakata

    Joined:
    May 8, 2008
    Location:
    Hilo, Hawai'i
    #4
    This isn't a "just use Google" response, but I wondering whether you searched for similar cases? I say this because a few years ago I was trying to set a friend's modem/router combo (Arris, I think) into bridge mode. I did succeed but not without plenty of Googling. What appeared to be straightforward instructions didn't work. Eventually I found what I was looking for on some message board, rather than on any manufacturer's site, or the cable company's site.

    I remember being surprised at just how many sites and forums devoted to cable modems and routers were out there. I don't remember any of them, unfortunately. But they are out there.

    If you haven't done this and decide to give it a try, be sure to tack on the modem/router's model number.
     
  5. adam9c1 macrumors 65816

    adam9c1

    Joined:
    May 2, 2012
    Location:
    Chicagoland
    #5
    What is probably happening is Crapcast is pushing out a firmware update and it resets their modem/router to default config.
    Honestly I'm not sure if there is a way to use their device in bridge mode. You can use your TC in bridge mode however.
     
  6. cwazytech thread starter macrumors 6502

    Joined:
    Jan 7, 2009
    Location:
    Colorado
    #6
    This has been the most common response. I can do it, but I was also looking to purchase my own Xfinity compatible modem so that I could return theirs. That would save me $10/month. Maybe I'll just suck it up.
     
  7. adam9c1 macrumors 65816

    adam9c1

    Joined:
    May 2, 2012
    Location:
    Chicagoland
    #7
    Yes, you can buy your own modem. Ask your support what's available in your area.
    Make sure you keep a good receipt as I've heard stores years later Crapcast says you are still renting or they did not charge you for rental and now they want $.

    If you have telephone service with them you have limited options.
     
  8. campyguy macrumors 68030

    Joined:
    Mar 21, 2014
    Location:
    Portland / Seattle
    #8
    Here's my fix, one that stuck after I figured out what was going on. It's not just a Comcast thing, or an Apple AE/TC thing - I've got offices on a few different ISPs, plus Comcast residential and business accounts. Once I figured it out - using Console and Little Snitch - it was a stupid simple fix, especially when I found that all of my CL fiber or all of my Comcast cable connections were pretty much crapping out at about the same time. If you followed the instructions, like I did, it just works - until it doesn't...

    Comcast pings their modems for lots of reasons, with firmware updates being the least likely reason - lease renewals are more likely. What happens at these lease renewals is a soft reboot of the modem - which includes temporarily reactivating the DHCP server built into the router and temporarily reactivating NAT, and you know the rest. Double NAT, and a need for a double expresso or a double Irish Whiskey...

    Almost all of my cable modems ship with a default 192.168.xxx.xxx address (the one I'm on now - a Netgear CM500 uses 192.168.100.1 but the Motorola SB6141 I used before that uses 192.168.1.1 and IMO there's issues with this "older" but still common address, read on). Following the installation instructions for your AE/TC relative to any of Comcast's modems (all of mine are purchased from a reseller, even for my BCI accounts - this does not matter here) generally yields a iPv4 DHCP Range of 192.168.1.2 to 192.168.1.200.

    With my SB6141 and a couple of the BCI-issued modems were trying to temporarily assign the same DHCP Range of 192.168.1.2 to 192.168.1.200 during this lease renewal that the AE/TC is trying to assign to your network, and there's your Double NAT issue...

    There's two fixes, on in software and the other in hardware. The hardware fix is simple - buy a modem that uses a different IP address, like the newer Arris SB6183 or CM500 - both use the same Broadcom chipset and 192.168.100.1 address.

    Before I ponied up for a few new modems, the software fix is to change in Airport Utility from the iPv4 DHCP Range of 192.168.1.2 to 192.168.1.200 to one of the two different options - after switching (in the Utility's Network>Network Options... settings) to a Range of 10.0.1.2 to 10.0.1.200 I have had zero issues between my modems and AE/TC devices and other routers, and zero down time. Once a week, my modems phone home, eventually sync and get a new lease, and I never notice a thing...

    Get your AE/TC/router DHCP Range assignment as far away as you can from the router's default IP range - or just on a different range of numbers. I hope this helps. If it does, mail a couple of fingers of Irish Whiskey to me - you won't need it!
     

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