I keep losing connection to the internet

I have a network router question. I live on a campus of a small African college and help them with computer stuff. The campus here has a cisco router as the main one that connects us to the internet. There are then various other routers, switches, etc. around campus. One of the other smaller routers is a Linksys wireless router that is near to where we live that provides wireless access to the network for people like us. The wireless router periodically stops being able to give us access to the internet. Sometimes this happens every hour, sometimes it can work for days. So the symptom is that everything will be working normally and then all of a sudden, I can't access the internet, but I can access anywhere else inside our LAN. And it's not just our computer; all the computers that are connected to the wireless router stop being able to access the internet. I can't even ping an address outside of our LAN.

The wirelss router has a static IP address. The way to make it start working again is to change the static IP address. When I do that, everything works fine again. And it's not just a matter of rebooting the wireless router. If you reboot it without changing the IP address, it doesn't work. So that (along with the fact that I can still access anywhere inside the LAN when the internet stops working) makes us think that it's not a problem with the wireless router itself, but with the main Cisco router, that it somehow only lets a limited amount of internet traffic through to the wireless router's IP address and then cuts it off until the its IP address changes. When this problem is occurring, I can ping, which is a computer on the network on the other side of the router. But I can't ping, which is an ip address used by Yahoo. As far as our wireless router goes, both and are outside, so why would I be able to ping one and not the other.

Have you ever heard of something like this? Do you have any ideas on this? Thanks, John

Reply to
Big Daddy
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On Tue, 19 Feb 2008 23:18:02 -0800 (PST), Big Daddy wrote in :

The most likely cause is that the low end wireless router is falling over from too many connections, probably because of illicit filesharing. It wasn't designed for this kind of use.

  1. Get rid of the illicit filesharing.
  2. Try DD-WRT firmware is your unspecified wireless router is supported.
  3. Get a better (e.g., Cisco) wireless router.
Reply to
John Navas

More information to respond to questions and comments:

I don't think the wireless router is failing because of too many connections. There are at most 10 people connected and I don't think that any of them are the types that would be doing illicit filesharing.

This has happened with two different wireless routers. We had one last year that was also Lynksys, and it was having the same problem. We replaced the firmware with DD-WTR, and it didn't help. We replaced the router with a different one last summer. At first it seemed to be better, rarely needing to have its IP address reset. But the performance has slowly degenerated to needing to be reset multiple times a day.

I am not using a multihomed computer.

I have tried using a static ip address with my computer and getting dhcp from the wireless router. I have tried setting the dns servers myself or just accepting the default given from the router. These things don't make a difference.

The wireless router has a static ip address of The main router from our campus to the internet has an address of The DHCP server for most of the campus is a computer with address It gives out ip addresses generally in the range of to, because there are fewer than 100 things that need an ip address on the network, but I haven't checked it to make sure that it isn't giving them out in the range close to, though I can't get a ping response from anything near there, so I don't think it's actually giving out any addresses conflicting with the wireless router's static address. I can try to check on that.

The wireless router is configured to be a dhcp server and give out addresses in the range to, so that none of the computers connecting to it have addresses that could interfere with other computers on the network. The wireless router's local ip address (i.e. what it looks like to my computer attached it) is

So even when I can't ping addresses on the internet, I can ping an address that is on our LAN like, but is on the other side of the wireless router from my computer (i.e. on the WAN side of the router).

When I do ipconfig /all on my computer, this is the output:

Windows IP Configuration

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

Ethernet adapter Local Area Connection:

Media State . . . . . . . . . . . : Media disconnected Description . . . . . . . . . . . : Broadcom 440x 10/100 Integrated Controller Physical Address. . . . . . . . . : 00-15-C5-CC-0C-E4

Ethernet adapter Wireless Network Connection:

Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Dell Wireless 1390 WLAN Mini-Card Physical Address. . . . . . . . . : 00-19-7D-18-5B-4E Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : Subnet Mask . . . . . . . . . . . : Default Gateway . . . . . . . . . : DHCP Server . . . . . . . . . . . : DNS Servers . . . . . . . . . . . : Lease Obtained. . . . . . . . . . : Thursday, February 21,

2008 9:59:14 AM Lease Expires . . . . . . . . . . : Friday, February 22, 2008 9:59:14 AM

Thanks for any more insight.

Reply to
Big Daddy

On Thu, 21 Feb 2008 05:56:53 -0800 (PST), Big Daddy wrote in :

Check the logs. You might be surprised.

That suggests your problem isn't the router.

I'm not surprised -- it doesn't sound like that kind of problem.

Why would you want to do double NAT? That can be a source of problems. Why not configure your wireless router as a wireless access point, and leave the NAT and DHCP chores to the main network?

Reply to
John Navas

Big Daddy hath wroth:

Any particular model number wireless router or wireless access point? Numbers are a good thing.

Note the chart at:

showing the maximum number of simultaneous connections for various low end wireless routers. Many of these low end routers start to drop connections at 8 or 16 users. Note that a random association from a distant wireless client that doesn't move any traffic counts as a connection. It's not unusual for my coffee shop networks to show 3-5 active users, but well over 25 associations.

Reply to
Jeff Liebermann

It's unlikely to be causing the current trouble. There's nothing wrong with leaving it setup with a NAT. It offers a somewhat limited form of security in that it isolates the users on it from the upstream network. Not completely but often 'enough' to avoid issues. Setting it up as an access point would not do that. That and the upstream DHCP would need to have enough addresses setup for leases.

I considered the possibility of DHCP lease conflicts/exhaustion but re-read your original message and saw it as unlikely to be the issue.

You're going to need to involve the people running the upstream cisco router. It sure sounds like that box is deciding to stop routing to this unit "for some reason". You're unlikely to be able to find out the reason without asking them about it. Changing a unit's IP address and having it suddenly start working again sure sounds like something on the cisco made a decision to stop routing to the old address. Find out what and then work with them to deal with it. If this is not an authorized device to be connected to the network then you're in for some trouble...

-Bill Kearney

Reply to
Bill Kearney

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