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I'm new(ish) to networking and have been setting up a home server. Part of making sure the server is good and healthy is of course making sure I have a solid connection.

Unfortunately, our DD WRT router needs to be reset at least weekly. No one uses P2P on our network, at most there are only a few standard machines doing basic web browsing at any given moment.

Last night was the first time that I ever had a chance to get to the route of the problem, and to try a less aggressive method to repair connection rather than resetting the whole machine.

So I ping(ed) but received no response. I was then forced to fix the issue immediately by one of the other LAN users; however, rather than resetting the router, I released and renewed the DHCP lease and connection was restored.

Leaving the routers WAN port, the next machine down the line is the modem and then off to Comcast it goes. We seem to have had problems with the same symptoms for the last three routers, all of which were Netgear/Broadcom machines, the last two ran DD WRT.

So I have three questions:

  1. Who is at fault? ISP or DDWRT?

  2. What tools can I use to more intelligently diagnose the problem than checking if a known server like Google's DNS is reachable?

  3. How can I make sure DD WRT takes care of this problem itself, even if I cant fix the route cause. For example, I have considered writing a script that pings a known server, such as, at regular intervals. If no response, a log is made of how far the machine makes it (using tools like question 2), and then the DHCP is released/renewed. I feel as though a more elegant solution should exist.

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up vote 4 down vote accepted

I have actually run in to this exact same problem myself, several times. (In one case the problem turned out to be an improper power supply on one of my routers, so much sure you check ALL the basics first.)

  1. As for who's at fault, I would blame consumer level equipment. These little Netgear/Linksys/etc boxes have never been the bastion of reliability, and there's also nothing elegant about them.

    • Check your WAN IP address. I've had junky modems temporarily hand out a 192.168.100.x address to my router while it picks up a proper IP address. Sometimes my router would get stuck here, rather than picking up the public IP.
    • If you want to drill down in to what's going on there, shove a hub (not a switch) in between the router and modem, then sniff the packets from a computer using Wireshark or Microsoft Network monitor.
    • You could also use tcpdump from your DD-WRT router for troubleshooting
    • It can also be helpful to enable logging on the DD-WRT router and take a look at what events pop up.
  2. Personally, I would stop fighting with it and go ahead and set up your script. Check, release and renew if that's down, and if that doesn't work reboot. Problem solved. If the problem isn't solved, smash your modem in to tiny little pieces and get a new one.
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Would traceroute be a good tool for @lakechfoma to use in this situation? I'm thinking he could see where in the line his connection is getting hosed up. – Kruug Jan 18 '13 at 16:24
@Kruug Maybe. I imagine when the connection's down all he will see is responding and nothing more. – Tanner Faulkner Jan 18 '13 at 16:32
@Kruug I was thinking traceroute would be useful here. It would be my first time using it, now I'm just waiting for the thing to fail again. Either way, I will definitely get that script running and a UPS for the whole setup. – lakechfoma Jan 19 '13 at 1:19

As noted by @r.Tanner.F consumer grade hardware can have issues.

One of the most common is they do not tolerate heat or bad power well.

Make sure there is ample air circulation and avoid stacking other hardware like modems or switches.

Power is best addressed by installing an UPS so that you get a steady 120/240V. I have seen many clinets with issues solved with a good UPS. Spikes are usually not the issue but rather brownouts and low voltage in general. It seems to send =the device into a weird state where it may not work at all or some functions fail.

In any case, a good UPS is always a good idea.

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+1. Power problems can get weird. I once had a router that refused to renew DHCP if my dryer was running on the same circuit. (Granted all my electrical is a mess but still.) – Tanner Faulkner Jan 18 '13 at 16:22
Do all UPS's do a good job of keeping mains steady, and if not can I trust that a UPS approaching $100 from staples will? – lakechfoma Jan 19 '13 at 1:11
Seems to me that a good router should have a good power filtering device built in. I'm just thinking that the cost of a little better router would be less than a cheaper router + a UPS. – Sablefoste Dec 1 '14 at 17:39

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