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    • CommentAuthordempseyw
    • CommentTimeDec 11th 2011
     permalink
    I've got a Motorola SB5101 cable modem from Comcast. There really aren't any settings I can change within it's configuration. The config page (192.168.100.1) only allows you to see some rudimentary settings but not really change anything. I bought a MediaLink (MWN-WAPR150N) wireless router to have WiFi in the house and it works great but I want to use OpenDNS servers configured on the router so I don't have to touch every device in the house. I can setup the OpenDNS server entries on the MediaLink router but it doesn't seem to make a difference. All the computers in the house are still using the DNS servers from the cable modem. Is there a way to either change the DNS entries on the cable modem or have the MediaLink router override the settings from cable modem?

    Thanks,
    Dempsey
    • CommentAuthorrotblitz
    • CommentTimeDec 11th 2011
     permalink
    You need to connect the computers with the MediaLink wireless router. You say the Motorola modem/router has an IP address of 192.168.100.1. So, what are the IP addresses of the MediaLink router, and what are the IP addresses on the computers?
    • CommentAuthormrbidou
    • CommentTimeDec 12th 2011
     permalink
    Changing the settings on the router and enabling DHCP on the router and all the computers and making sure ALL the computers connect to the router, should be all you need to do. The router will by-pass the modem DNS if you assign static DNS servers in the router settings. Then if all the wired and wireless computers are set to use DHCP (no static IP) then they will use the DNS set in the router. (the modem ethernet port must be connected to the WAN or Internet port on the router for all this to work properly.
    • CommentAuthordempseyw
    • CommentTimeDec 12th 2011
     permalink
    All the computers in the house are connecting through the wireless router. The only thing connected to the cable modem is the MediaLink router. DHCP is enabled on the MediaLink router with the static OpenDNS DNS Servers configured. But when I do an ipconfig on any of the computers connecting over the wireless they show the DNS servers that the cable modem is getting from Comcast. That's the weird part to me. Even though DHCP is configured on the router and the OpenDNS servers are set the devices are using the Comcast DNS servers instead of OpenDNS.

    I've found people that have hacked the SB5101 modems for ill-gotten gain (free Internet) but I'm not looking to do that. I just want to be able to use OpenDNS. So I was wondering if there was a backdoor to the modem so I could change the DNS Server entries there since that seemed to be the source of the problem. But if one of you guys can show me the error of my ways with the wireless router configuration I'll take any solution I can get.
    • CommentAuthorrotblitz
    • CommentTimeDec 12th 2011
     permalink
    See my first questions? They are still not answered.

    The problem seems to be that your computers use the MediaLink computer only in regards to WLAN, but for everything else (not only DNS) the Motorola device. Answering my questions regarding the IP address subnet being used at each device could help us to advice how to proceed.

    You can post the output of "ipconfig /all", the IP address from the LAN side of the Medialink and also the WAN facing side of the MediaLink status page which should be the same as the LAN facing IP address of the Motorola status page.
    • CommentAuthorsndlight
    • CommentTimeDec 13th 2011
     permalink
    Hi folks,
    I'm just now experiencing a very similar problem. Have a medialink router connected to a comcast cable modem. Set the DNS on the medialink to opendns servers. Until about a week ago, this worked fine--all my computers received the opendns dns settings. Then about a week ago, my modem froze and stopped working despite being connected to a UPS, and I ended up resetting the modem. Today, I noticed that the DNS settings didn't take...the medialink router shows that my dns settings are opendns, but ipconfig on my wirelessly connected laptop shows comcast dns settings. This is despite an ipconfig/release then /renew and a "repair" of the network connection. The DNS was definitely set to receive its values via dhcp. Something VERY strange seems to be going on.
    • CommentAuthormaintenance
    • CommentTimeDec 13th 2011 edited
     permalink
    You have to reconfigure the network when you reset or change equipment. The routers are probably bridged instead of NATted, and the Medialink is now a passive device.

    But anyone who needs further assistance with these apparently similar problems should answer the questions already asked.
    • CommentAuthordempseyw
    • CommentTimeDec 13th 2011
     permalink
    rotblitz,
    The IP address of the MediaLink router is 192.168.0.1. One of my computer's IP is 192.168.0.102 (the DHCP server is starting at 100). Thanks for any help you can provide.

    This is the output from the ipconfig /all:
    Windows IP Configuration

    Host Name . . . . . . . . . . . . : SlammaJammaPC
    Primary Dns Suffix . . . . . . . :
    Node Type . . . . . . . . . . . . : Hybrid
    IP Routing Enabled. . . . . . . . : No
    WINS Proxy Enabled. . . . . . . . : No

    Ethernet adapter Local Area Connection:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Broadcom 440x 10/100 Integrated Controlle
    r
    Physical Address. . . . . . . . . : 00-1A-A0-1C-91-0E
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    Link-local IPv6 Address . . . . . : fe80::4007:b451:240e:8ebc%9(Preferred)
    IPv4 Address. . . . . . . . . . . : 192.168.0.102(Preferred)
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Lease Obtained. . . . . . . . . . : Monday, December 12, 2011 11:06:03 AM
    Lease Expires . . . . . . . . . . : Tuesday, December 13, 2011 11:05:42 AM
    Default Gateway . . . . . . . . . : 192.168.0.1
    DHCP Server . . . . . . . . . . . : 192.168.0.1
    DHCPv6 IAID . . . . . . . . . . . : 184556192
    DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-0E-0B-83-A9-00-1A-A0-1C-91-0E

    DNS Servers . . . . . . . . . . . : 75.75.75.75
    75.75.76.76
    NetBIOS over Tcpip. . . . . . . . : Enabled

    Tunnel adapter Teredo Tunneling Pseudo-Interface:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes
    IPv6 Address. . . . . . . . . . . : 2001:0:4137:9e76:18ad:3f0:3f57:ff99(Prefe
    rred)
    Link-local IPv6 Address . . . . . : fe80::18ad:3f0:3f57:ff99%11(Preferred)
    Default Gateway . . . . . . . . . : ::
    NetBIOS over Tcpip. . . . . . . . : Disabled

    Tunnel adapter isatap.{447F161B-187B-4918-B7E8-4D4D55473EA6}:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes
    • CommentAuthorsndlight
    • CommentTimeDec 13th 2011
     permalink
    This is from the router:

    Network status:
    Connection Status Connected
    WAN IP 68.34.0.113
    Subnet Mask 255.255.254.0
    Gateway 68.34.0.1
    Primary DNS Server 208.67.222.222
    Secondary DNS Server 208.67.220.220
    Connection Mode Dynamic IP

    Service Status:
    IP Address 192.168.0.1
    Subnet Mask 255.255.255.0
    DHCP Server Enable
    NAT Enable
    Firewall Enable

    System Status:
    System Time 1days 02:36:04
    System Date 2011-12-12 Mon 20:27:17
    Connected Clients 3
    Firmware Version H2_V3.3.5w_MDL_02
    Boot Version 2.1.0
    LAN MAC Address C8:3A:35:5F:0D:E0
    WAN MAC Address C8:3A:35:5F:0D:E5
    Hardware Version 2.0


    This is ipconfig /all on the computer
    (after I've done an ipconfig /renew):

    Ethernet adapter Wireless Network Connection:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Intel(R) Centrino(R) Advanced-N 6200 AGN
    Physical Address. . . . . . . . . : 58-94-6B-etc...
    Dhcp Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    IP Address. . . . . . . . . . . . : 192.168.0.103
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.0.1
    DHCP Server . . . . . . . . . . . : 192.168.0.1
    DNS Servers . . . . . . . . . . . : 68.87.73.246
    68.87.71.230
    Lease Obtained. . . . . . . . . . : Monday, December 12, 2011 8:29:33 PM

    Lease Expires . . . . . . . . . . : Tuesday, December 13, 2011 8:29:33 PM
  1.  permalink
    I would say that both of these routers are being used as passive wireless access points, which is quite likely if you did no manual configuration.

    See your documentation for further information (see WDS among other things), but you want to turn off DHCP on the gateway, and turn it on on the wireless router. You want the gateway to act as nothing more than a modem, and the wireless router to act as a router and not a plain AP.
    • CommentAuthordempseyw
    • CommentTimeDec 13th 2011
     permalink
    maintenance,

    I did a tracert from that computer and talked with a friend of mine at work who uses Comcast. He said that Comcast doesn't allow dynamic DNS and the tracert seems to prove that out. It didn't show the OpenDNS servers at all, it was Comcast servers only. So the root of the problem could be this Comcast policy.

    I haven't found any rule on their site telling me that I have to use the Comcast DNS server so I'm still on the hunt for a way to override their DNS server addresses on the cable modem. But they've locked down the configuration settings on the SB5101 really tight and I need a backdoor to be able to change it. Anyone have any ideas?
    • CommentAuthorrotblitz
    • CommentTimeDec 13th 2011
     permalink
    Neither these:

    "DNS Servers . . . . . . . . . . . : 75.75.75.75
    75.75.76.76"

    nor these:

    "DNS Servers . . . . . . . . . . . : 68.87.73.246
    68.87.71.230"

    are OpenDNS resolver addresses. Are these configured statically on the computers, or are these being obtained via DHCP? You must shut down the DHCP server on the Motorola device. There must not be more than one DHCP server running in a network.
  2.  permalink
    "He said that Comcast doesn't allow dynamic DNS and the tracert seems to prove that out. "

    No, not really. As you know, you aren't using OpenDNS for lookups. And I'm not sure what dynamic DNS has to do with the issue here.

    What about a traceroute indicates... something? I haven't seen it so I'm not sure what data you are interpreting.
    • CommentAuthordempseyw
    • CommentTimeDec 14th 2011
     permalink
    rotblitz,

    Those addresses must be coming from DHCP on the cable modem. That lead me to the same conclusion as you - I need to shut down the DHCP server on the Motorola cable modem. But Comcast has the modem completely locked down (there is no configuration page provided where you can change any of the modem settings), which is why I'm trying to figure out if anyone knows of a hidden config page (or the like) on an SB5101 Motorola modem that will let me turn off DHCP?

    Anybody?
  3.  permalink
    Not very likely. But you can ask in fora where people hack routers/modems. It isn't just a SB5101 Motorola, but with whatever firmware Comcast uses. Realize also that if you are able to alter the configuration, you may lose internet connectivity and void the warranty on the device, as well as violate Comcast's terms of service.

    Not sure why you are worried about DHCP on this device, though. You need to turn it off for the WAN on your other router.
  4.  permalink
    @dempseyw: Hi. Did you ever fix that problem with medialink? Thanks.

This discussion has been inactive for longer than 30 days, and is thus closed.