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Solved: Modem "steals" connection?

Discussion in 'Networking' started by jmc, Jul 25, 2006.

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  1. jmc

    jmc Thread Starter

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    I've recently moved to Australia, and got service with an ISP here. They provided a modem that thinks it is a router (it has router-like configuration options, though it is single port). I also have a D-link 614+ wireless/wired router. This is the first time I've had broadband configured properly - wall to modem to router to computer.

    This computer connects to the router via cable (and never loses internet connectivity); a computer and a laptop connect wirelessly. What is happening is that when the wireless clients boot, they can't find a network connection. When I go to a command prompt on this PC, and use ipconfig /all, the modem's IP has replaced the router's in default gateway, DHCP and DNS servers. I can't even connect to the router through it's IP address.

    I can disconnect the router's power and reconnect it, and it will work properly once again, and reappear where it should in ipconfig. This wasn't happening when we first set this up nearly a month ago, started happening this weekend.

    The router was configured when I had a different setup: I had a USB modem with no ethernet ports, so internet access was provided via software proxy on this workstation. The modem I now have came preconfigured. Since everything worked when I set up this connection, I didn't make any configuration changes.

    Any idea what's happening here? Do I have to configure one or the other so they don't interfere with each other? Thanks for any help!
     
  2. StumpedTechy

    StumpedTechy

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    Well first off I don't see a modem model or type or brand anywhere in your post that may help. As well telling us the ISP may help as well.

    Here is how I would do it if you have a modem/router and another preconfigured router. 1) Hard reset your router this is different per make and model but most have a little reset button you hold down as you power it off and then keep it held down during power on for about 5-10 seconds and let go.
    2) Direct connect the PC to the modem/router and go to its configuration page and see if there is any way to stick it into bridging mode.
    3) Unplug the PC and put the router on.

    If there is no bridging mode on this modem/router combo then look into this -
    1) See if the modem/router is set to DHCP and to multiple leases. 2) see if it has an adequate port forwarding setup. If these are good and you can live with it I would then follow Johnwills post on connecting 2 soho routers (found by searching this forum he usually posts it about once a day.)
     
  3. TerryNet

    TerryNet Moderator

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    I ditto what StumpedTechy posted. Both Dhcp servers are enabled (the modem/router and your wireless router) and, I found by accident one day, it's random which will respond first to a PC requesting an IP configuration. At the very least you want to disable one of these servers, but best is to do as StumpedTechy said--bridge (bypass) mode in the modem/router or the JohnWill 'connect two soho".
     
  4. JohnWill

    JohnWill Retired Moderator

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    For your reading pleasure: :)

    Connecting two SOHO broadband routers together.

    Configure the IP address of the secondary router to be in the same subnet as the primary router, but out of the range of the DHCP server in the primary router. For instance DHCP server addresses 192.168.0.2 through 192.168.0.100, I'd assign the secondary router 192.168.0.254 as it's IP address.

    Disable the DHCP server in the secondary router.

    Setup the wireless section just the way you would if it was the primary router.

    Connect from the primary router's LAN port to one of the LAN ports on the secondary router. If there is no uplink port and neither of the routers have auto-sensing ports, use a cross-over cable. Leave the WAN port unconnected!
     
  5. jmc

    jmc Thread Starter

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    First, let me clarify. I'm not sure the modem's a router, or maybe it's "function confused". Outside, it's a modem - one ethernet port. On the inside, it seems to be a router - I configure through an IP address, and the options available are similar to my router's. However, the problem would be that the modem is NOT wireless capable, and it's the wireless clients that are experiencing problems.

    The modem identifies itself in setup as an iConnect Access 621, which I don't think will be helpful (ISP is iiNet, an Australian company). Elsewhere, it says it's an OPEN Networks DSL Modem, and when for a little while it was connected via USB, the computer saw it as a TI something or other. Seems to have a personality problem, wot?

    Unfortunately, I'm not sure I can follow Johnwill's advice for my problem. As I read it, I'd have to set the modem as the primary router, but don't think I can (see above).

    I found "bridge filters" in the modem's setup, requests a source mac & port, destination mac and port, and allow/deny. This is what you mean, right? I set this up in the MODEM and it'll allow the WIRELESS ROUTER to do it's job without interference? The real router doesn't seem to have a similar option.

    I also found these other settings that might be useful:
    - a checkbox set to "default gateway". The router should be my network's default gateway, right?
    - "Enable DHCP Server" is checked, and has an IP address range that's in the same subnet as the modem, but that's a different subnet than my network/router (the ISP help told me when asked that it was OK to leave the modem's IP unchanged). It also has "Enable DHCP Relay" which I'm not familiar with but looks promising. I can also turn both off.

    In the end, as I understand these things, I want the modem to provide internet access to the router, and I want the router to parcel it out to the wired and wireless clients. Right?

    What I don't understand (well, besides how to fix this) is why this is happening *now*. They've been working quite happily together for just under a month; I haven't made any changes to my system, at all, during that time. Why is this suddenly starting to happen? What could be triggering the change in DHCP Server, DNS Server and Default Gateway?

    As always, any help appreciated! Sorry I'm so verbose.
     
  6. StumpedTechy

    StumpedTechy

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    Well your modem is definitely a modem/router -

    http://www.getnow.com.au/catalogue/c13/p160

    Also I know it can be set to bridged -

    now the question is How. if you want can you provide some screenshots? I'll keep an eye out for a manual but as you mention the pickings look slim.

    I would not worry about its actual numbers usually I have seen a few devices that whats labeled on the box and what device manager show are totally different.

    Yes if you set the modem/router to bridged mode then your router does not need to be set to bridged mode as well.


    If you find the setting to turn it into bridged mode both of these should negate to whats needed for ocnnection and you shouldn't have to play with it.

    What you say is correct and the reason its happening now is probably due to some DHCP battle going on between the 2 devices. The fact that its been setup incorrectly from day 1 though is evident if you take a modem router and then plug in a router on top of it your bound to have some issues.
     
  7. jmc

    jmc Thread Starter

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    Thanks. I tried to simply turn off dhcp on the modem/router and all heck broke loose (the short version: completely lost access to the modem. Utterly. got it back tho or I'd not be writing this). I finally got it all working again and now it's an hour past my bedtime. I'll try the bridge tomorrow, but after what just happened I'm a little reluctant.

    Well, iinet calls it a modem and told me I'd not have to reconfigure it, even after I told them how my network would be set up. Though, I've just noticed on the "easy setup" paperwork, it's called a router there. duh.

    I'll try bridging tomorrow. Thanks for everyone's help. Moral of the story:

    DON'T MESS WITH YOUR NETWORK SETTINGS 15 MINUTES BEFORE BEDTIME. I'll print a big banner up tomorrow :)
     
  8. TerryNet

    TerryNet Moderator

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    Sorry, I was too hasty when I said, "At the very least you want to disable one of these servers." With your current physical connections, turning off the primary router's Dhcp server would, of course, necessitate setting a static IP on the secondary router's WAN side. Guess I should have mentioned this. :(

    I think that the reason your network was working for some time and then started acting up is as I said before: "it's random which will respond first to a PC requesting an IP configuration."

    I think that the "bridge filters" in the modem/router's setup is NOT the bridge mode that StumpedTechy is talking about; as I understand it bridge mode should be a simple on/off thing with bridge mode on meaning that the modem/router bypasses the router function and acts like a modem only. By the way, "router" does not imply multiple ethernet LAN ports; many of these ISP supplied modem/routers seem to have one port--you add a switch if you want to have multiple PCs.

    To go JohnWill's route, you need change NOTHING on the modem/router (unless the Dhcp Address range is severely restricted). It's just the secondary router that needs to be configured.
     
  9. TerryNet

    TerryNet Moderator

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    I found this:
    -----------------start copy--------------------
    iConnect Access 621

    Open 192.168.1.254

    Enter the username root and the password 0P3N

    Click the Setup button at the top
    Click DHCP Configuration
    Place a dot next to Server and Relay off.

    Now click Connection 0 (on the left hand side).
    In the Type box (top right) select Bridge
    Click the Apply button at the bottom

    The modem should attempt to test these settings, wait for this to complete.

    If the IP address will conflict with your router:
    Click Management IP on the Left
    change the IP address to 192.168.7.1 and click apply
    remember to note down the IP address

    Click the Save settings link on the left hand side
    -----------end copy------------------------

    You can find the full text here: http://forums.whirlpool.net.au/forum-replies.cfm?t=393139
    and I think that you need to read the cautions before proceeding.

    It was in answer to "iConnect Access 621 - Turn off router ?".
     
  10. jmc

    jmc Thread Starter

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    TerryNet:

    Yup, that's what I did last night. Not sure what happened but I thought I'd killed the modem, when what happened is something went pear-shaped on the PC side. Rebooted the pc, reset the modem to factory settings, hooked it all back up, ensured it was back in working order, posted here and went to bed :)

    Kudos to Rob at iiNet though, he was great, and understood - when I stopped the call as my computer wouldn't boot (at that point I was resetting it), he told me to be sure I called him back if I couldn't sleep. Which is what usually happens - I'll be up till 3am 'cause I can't go to bed until the problem's fixed!

    Today I got a note back from iiNet that said essentially the same thing that you did (which was the same thing I did last night). Did it again though, and this time everything is still working. So thank you. Glad I didn't try the bridging filters though, it didn't really sound like the same thing to me either, since it could accept multiple (like 10 or 20) different filters.

    All's well now, there hasn't been an IP-stealing incident all evening :)

    jmc
     
  11. TerryNet

    TerryNet Moderator

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    Great! Hope you can sleep peacefully now. :)
     
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