My new router is not obtaining an IP address from my cable modem

My new router is not obtaining an IP address from my cable modem
My new router is not obtaining an IP address from my cable modem
2018-11-07 19:43:47 - last edited 2019-01-29 18:33:50

Have you ever unboxed your brand-new router, hooked it up to your existing cable modem and nothing happens?  The awesome new device you just purchased doesn’t go online and the internet light stay amber or red.  Believe it or not this is actually a common issue referred to as MAC Binding.  Essentially what is happening is the Modem is still bound to the MAC (media access control) address from the last device that was connected to it.  When the modem looks to hand out the public address from your ISP it does not recognize the address being offered so it does not give out the IP address.  Its like trying cash a check without ID, no verification so doesn’t work. 

 

So how do we fix this?  Well, that’s very simply really.  Frist you will want to unplug the power cable and the coaxial cable from the back of the modem. Next connect your router to the modem via ethernet, but please make sure the ethernet cable is in the WAN port on your router.  Then reconnect the power cable and power on your modem but leave the coaxial disconnected.  Wait 3 to 5 minutes to give the modem enough time to flush its memory, then reconnect the coaxial cable.  Once the modem fully connects to the internet, check the router’s internet light it should now be good.  For TP-Link routers this means either White, Green or Blue depending on your model.  Check the internet and see if you can now reach your favorite websites.  In rare cases you may need to contact your ISP and have them clear the modem’s connection remotely.

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#1
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7 Replies
Re:My new router is not obtaining an IP address from my cable modem
2019-03-14 21:50:35

same problem was with me but when i was restart the device it does not happens some hours. May be new router has some technical issues 

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Re:Re:My new router is not obtaining an IP address from my cable modem
2019-03-15 18:59:49

@Maxwell 

 

 

That might be an indication of something else.  While the router may have issues its always best to start at the source and work back.  What i would suggest is logging into your modem and getting its logs.  For cable modems the address is typically 192.168.100.1.  You may need to obtian the log in credentials for the modem either from your ISP or online from the device manufacturer.  If its a TP-Link modem the username and password are both "admin" by default.  Once logged in look at the logs for any T3 or T4 Timeouts.  These indicate a service level issue which typically requires a maintenance dispatch.  If there are no T3 or T4 time outs next look at the Channels.  You will want to make sure your downstream channel power level is between -12 and +12 dBm on each channel.  Anthing outside this will require the ISP to make some changes to your service, most require a dispatch to your home.  Lastly the SNR on the Downstream should be mid 30s to 50 again if there is an issue the ISP will need to fix it.   Upstream is never much of an issue so nothing there to really worry about. 

 

If the modem checks out then we would want to look at the router.  The first step for that is to do a Firmware update if available.  and if not then we would need to dig deaper into troubleshooting.  Please let us know if that needs to take place. 

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Re:Re:Re:My new router is not obtaining an IP address from my cable modem
2019-05-07 10:04:07

I have new device tp link c20... 

And i have installed point to point with my airgrid m5hp... 

This my topology

Modem Huawei 

Lan Ip address 192.168.100.1

Wan dhcp 192.168.100.2 - 192.168.100.254

 

Airgrid m5hp 

Lan Ip address 192.168.100.184

Gateway 192.168.100.1 

 

Airgrid m5hp 

Lan Ip address 192.168.100.185

Gateway 192.168.100.1 

 

Router tplink

Lan Ip address 192.168.10.186

Wan dhcp 0000

 

What are configurations should i change... Please help... My router don't get the dhcp dynamic ip address from my modem

 

The wan don't get the dhcp dynamic ip... 

I think the problem on ip router or gateway.

I am new here,when i try to connect to my airgrid with router connected the webui of Airgrid wont load.When i connect the ethernet cable to my pc then it loads up just fine. is there a way to access the Airgrid while my ethernet cable is connected to m router.

 

Thanks.

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Re:Re:Re:Re:My new router is not obtaining an IP address from my cable modem
2019-05-08 18:28:14

@Ayufrida07 

 

I see you are located outside of the U.S.  This particualr community is only for customers in the U.S and Canada.   We do have a community for other users though at https://community.tp-link.com/en.  Please resubmit your question there and the team that are experts in your region will assist you. 

 

 

Thank you 

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Re:My new router is not obtaining an IP address from my cable modem
2019-07-04 02:27:38
Trying to set it up no security code is coming up
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Re:Re:My new router is not obtaining an IP address from my cable modem
2019-07-08 17:40:56

@Kemonie01000000 

 

 

Sorry I was out due to the 4th of July holiday.  Were you able to resolve this issue?  If not please provide me with more information so i can assist. 

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Re:My new router is not obtaining an IP address from my cable modem
2019-10-01 14:12:07

@Carl I too have been having this probably recently. I had to restart my network and my C5400 would not obtain the IP address from the modem, even though the modem was on and connected to the internet. After a few resets this resolved.

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