Why does restarting/resetting the router work?

So, I'm a technology guy and sometimes I have to troubleshoot a home network, including my own. I make sure the wires are in securely and that the lights suggest there's an actual internet connection. Usually after that point I just reset the router( and possibly the cable modem) and that fixes things most of the time.

The problem is I'd like to know what sort of issue I could possibly be fixing by resetting the router.

EDIT: Just to clarify, I was speaking more about reset as in turning the router off and on. Still, any information about a hard reset(paperclip in the hole) is useful. So the more accurate term would probably be restarting

Also, personally I usually have to deal with D-Link or Linksys home routers. I generally only bother messing around with stuff if I can't make a connection to the internet at all.

Eugene M

Posted 2009-07-15T14:51:57.340

Reputation: 853

Do you include turning off or unplugging from the power and turning on again, when you say "resetting"? Maybe you just meain using "a paperclip in the hole" to reset. I've found a turn-off and on to fix certain problems. – Ash – 2009-07-15T15:03:07.290

Yeah sorry, I meant the more layman use of the term. I've editted the post to reflect that. I at least understand why resetting the firmware might fix things but just turning a router off and on seems like voodoo. – Eugene M – 2009-07-15T15:10:22.957

I would really like to know why my Modem/Router needs to be turned off, and then back on, instead of being able to just reboot it from its web interface. – Brad Gilbert – 2009-07-15T16:52:35.527

Answers

Software reloads often fix things like memory leaks and hung processes. I'm assuming your router runs a version of Unix that just isn't quite up-to-snuff.

What kind of router do you have? What firmware is it running? What problems are occurring?

Russ Warren

Posted 2009-07-15T14:51:57.340

Reputation: 2 523

1Exactly. After all, a router is essentially just a small computer. If rebooting fixes most problems for a computer, then it stands to reason that it would have the same effect for a router (or a modern game console, smartphone, Internet toaster, Japanese toilet, and any other device that has a computer in it). – Synetech – 2012-06-24T16:12:14.000

Sometimes you may have bad hardware (I have seen a number of Linksys Wireless APs where the transmitter would just stop after a while and needed to be reset by a physical power cycle)

Sometimes a software bug will lead to the router becoming unresponsive over time (e.g a memory leak)

Usually though it is just a workaround for something that can be done another way, but it is just quicker to reboot (I had a cable modem that would drop from time to time. It would come back up eventually after a timeout, but it was usually quicker to power cycle it to force the renegotiation).

Russell Heilling

Posted 2009-07-15T14:51:57.340

Reputation: 690

When I need(ed) to reset my router, I discovered that it was almost always because it couldn't renew its IP address. I've since learned that I can just log in to the router via its web interface and click Release and Renew and it nearly always solves the problem. It saves me a trip to the computer room.

BillP3rd

Posted 2009-07-15T14:51:57.340

Reputation: 5 353

Many sorts of problems can be fixed by restarts. Not only with routers, but with computers in general. :)

Usually this is a solution when, for some reason, the operating system of the machine in question (be it router, PC, phone, or pretty much anything else) becomes unresponsive for some reason - most probably due to a bug which leads to memory leaks, which over time slow down the system.

ibz

Posted 2009-07-15T14:51:57.340

Reputation: 459

Every router has it's original firmware stored somewhere on it.

When you reset the router you overwrite the current firmware and config with the original one. What usually is fixing the problem is that the config is overwritten with the original one. But in some cases you have an updated router that isn't working for some reason.

Ólafur Waage

Posted 2009-07-15T14:51:57.340

Reputation: 520

1"When you reset the router you overwrite the current firmware", hmmm, I never heard of that. I actually doubt that this is true. – Arjan – 2009-07-15T14:57:29.873

@Arjan van Bentem - it depends on the definition of reset. A power cycle would usually revert back to user settings held in NVRAM. A 'reset' may be just a power cycle or could imply a return to factory defaults held in ROM: this is sometimes done, for example, by pressing a reset button for several seconds when powering on. – mas – 2009-07-15T15:14:59.220

@Arjan resetting is the little button on the back of the router where you hold it in and reset it. Turning it on and off is just restarting. – Ólafur Waage – 2009-07-15T16:01:24.133

Still then: do most (surely not every) routers keep a factory firmware, just to be able to revert to that? (I've surely bricked a router in the past -- totally my fault.) – Arjan – 2009-07-15T19:36:48.190

Well with all routers I've worked with (SpeedTouch, Sagem, zyxel). You are unable to brick it unless you do something horrible in the routers console. – Ólafur Waage – 2009-07-17T00:34:05.400

Hehe, it was a Speedtouch I bricked. (Some hack to change a Home into a Pro? Long time ago for sure.) – Arjan – 2009-07-17T22:41:59.723

@Arjan I've been working with Speedtouch 545, 570, 580 and 585 and they all have the original firmware. I don't know about the Speedtouch Home. – Ólafur Waage – 2009-07-17T23:34:48.240

Restarting the router empties the DNS cache inside of it. There are times when a DNS cache contains out of date page info, and clearing it can make things work better. Windows and Linux have commands for flushing the dns cache without a restart. I can't say about routers.

The paper clip in hole generally causes a reset to factory condition. This can erase configuraton information that you need to make the network functional. For example, if your router is also a DSL modem/home gateway, you will lose the authentication info the router uses to log you onto the internet gateway.

Walter Mitty

Posted 2009-07-15T14:51:57.340

Reputation: 419