C3000 with hung DHCP process?

Question

I have a Netgear C3000 cable modem/gateway, connected to Comcast. Multiple Macs in the house, with both WiFi and Ethernet access to the gateway.

Everything generally works, but every few days one of our computers cannot get Internet access; if you examine Preferences/Network it shows that the machine has no IP address, and can't seem to get one.

This typically happens when a) a machine is awakend from sleep, or b) someone brings a new laptop to the house.

It is usually the case that another machine which has been running (i.e., has an IP address) can continue to access the Internet during this time.

So it appears that the basic router function is running, but it smells like a hung DHCP process in the Netgear gateway router. Indeed, if we re-boot the box, the computer then gets an address and can then access the Internet.

Has anyone seen this before?

Suggestions on how to fix it? [Other then having to reboot all the time......]

DarrenM · Answer

Hello Johninwoodside

&nbsp;

Have you tried to do Address reservation on your devices to see if it will save that IP and will not disconnect.

&nbsp;

DarrenM

JohnInWoodside · Answer

Thanks for the suggestion, and I did think of it.

a. A reserved IP address for each machine might help with devices that are regularly in the house -- but requires that I keep track of all the address assignments (and rather defeats the purpose of having DHCP to begin with!).

b. More importantly, that will NOT help with the case where my kids' friends bring over a laptop or phone with WiFi, and can't get an IP address -- "Dad, the Internet's broken again! Do I have to go re-boot it again?! Why don't you go buy a different router?!" It doesn't happen every time, but when it does a re-boot of the router seems to fix the problem -- but that's a nuisance (and supports the idea that DHCP is getting hung).

[Netgear has a terrible reputation for bad customer support, and I am now beginning to understand why people complain. Do any Netgear engineers actually monitor these boards?]

vkdelta · Answer

JohnInWoodside&nbsp;what FW are you running? (I would assume it is V2.02.06)Did you have this problem always or it recently?&nbsp;Is there anyway, you can share wireshark capture when the DHCP process is failing on your C3000?&nbsp;(wireshark capture on your PC when it does not get an IP, We would like to see if the device is NOT sending DHCP OFFER or DHCP ACK)&nbsp;

JohnInWoodside · Answer

vkdelta -- thanks for jumping in on this!&nbsp;--The web-based Netgear Genie page&nbsp;does show FW version v2.02.06. &nbsp;[As I understand it, this is pushed by the cable operator, Comcast.]&nbsp;--The problem has happened, on and off, ever since we got the Netgear modem/gateway. &nbsp;But it is intermittant -- can happen multiple times in one day, and then does not re-emerge for a couple of weeks.&nbsp;--I have downloaded a copy of WireShark 2.0.0, fired it up on a Mac, but do not really know how to use it. &nbsp;It's hard to predict when the problem will emerge.a. &nbsp;Can WireShark run in the background, even when the Mac goes to sleep?b. &nbsp;Is there an easy way to set it so that it only collects DHCP packets?&nbsp;Thanks again for your help!&nbsp;

vkdelta · Answer

I am assuming your Macbook gets stuck during DHCP process at times.&nbsp;here is short tutorial from external party. The key is choosing right Interface (ethernet or Wifi) and filter the packets. Put the filter as "bootp or dhcpv6 or dns" &nbsp;in the filter. this will capture DHCPv4, DHCPv6 and DNS packets.&nbsp;http://www.howtogeek.com/104278/how-to-use-wireshark-to-capture-filter-and-inspect-packets/&nbsp;&nbsp;a. &nbsp;Can WireShark run in the background, even when the Mac goes to sleep?&gt;&gt; I dont think it runs when MAC goes to sleep. to start with you can capture only when the issue happens&nbsp;b. &nbsp;Is there an easy way to set it so that it only collects DHCP packets?&gt;&gt; Please use the filter above.&nbsp;

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C3000 with hung DHCP process?

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