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Lose Internet Connection Periodically

By Dragon Emperor ·
When connected to the internet I have full access for a seemingly random amount of time. Sometimes I can go days, other times only a few minutes. Usually it is more like 30 minutes.

When the problem happens I cannot read email or browse the internet. I can still ping and access network computers. The only way to regain access appears to be a reboot.

I have wireless broadband.
All computers are running Windows 2000 SP 4.
I have an SMC Barricade 7004BR router and an Asante FriendlyNET switch.
All computers are protected by up to date firewalls (Sygate) and
antivirus (Panda).

The problem occurs when I directly connect to the broadband modem as well.

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by Dragon Emperor In reply to

It is a reboot of the computers. My router and switch have not required reboots yet (though I have tried in my troubleshooting).
I have a 512Kbps (both directions) wireless internet connection (usually runs closer to 650 both ways).
Unfortunately changing ISP isn't an option. I came to them from the only other broadband here (and my old ISP had poor line quality and consistently lower than paid for speeds).
They have already changed the wireless modem (which fixed their initial speed problem).

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by george In reply to Lose Internet Connection ...

If you can ping computers on the internet, but cannot surf the web or get email, then your problem is the DNS. If you are getting the DNS servers from you ISP, try to entering them manually in the TCP/IP options menue. If that doesn't work, try to use someone elses DNS servers.

You can check if it DNS by typing "nslookup www.google.com" or some other site. If you get "... can't find server: Non-exixtent domain", then type in "nslookup" and enter. At the > prompt, type "server 205.152.0.5" and enter (this will make bellsouth's name server as the active name server or use any DNS server you may know about). Then type in "www.google.com" and enter. If you get an IP address, then you know your problem is the DNS server. Please make sure you enter the commands above without the ".

Hope this helps.

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by Dragon Emperor In reply to

nslookup worked fine after the problem occurred. I tried it with a variety of domains and all worked fine.

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by Dragon Emperor In reply to Lose Internet Connection ...

1 system has gigabit ethernet, the others 100Mbps.
Disabling the antivirus and firewall does not help.
Both ping and nslookup work fine.
tracert never works, but it gets as far as it always does (can't make it past their 1st router).

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by Dragon Emperor In reply to Lose Internet Connection ...

Point value changed by question poster.

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by Dragon Emperor In reply to Lose Internet Connection ...

Windows 95b (I have a multiboot system that can go into several systems) seems unaffected by the problem, while all of my Windows 2000 machines are affected.

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by mobiletech4u In reply to Lose Internet Connection ...

my question to you is how many pc's are connected to your router and you say you have a switch so you must have quite a few computers connected have you tried checking the event viewer it is a tool for troubleshooting also have you installed performance monitor you can use it for a varitey of reasons.
hope this helps

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by mobiletech4u In reply to

after reading your comments are you using a cross over cable with the switch or just a patch cable with a switch a cross over cable is needed.

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by Dragon Emperor In reply to

I only have a handful of computers on my LAN.
I am using a crossover cable.
And the problem happens when I take the systems off of the LAN and just connect directly to the modem.

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by shmaltz In reply to Lose Internet Connection ...

Here is what I gather the facts are:
1. Win2k machines
2. Win9x machines don't have this problem (although I don't know how you tested this since it happens randomly, it could just be that the 9x machine wasn't in the mood of making trouble).
3. When you reboot the OS (win2k) that machine doesn't have the problem anymore.
4. The router doesn't have to be rebooted for the computers to clean up the problem, just the computers have to be rebooted.
5. The modem is not the problem, also because a reboot from just the computer will help, without rebooting the router/switch/modem.
Here is the troubleshooting technique you should use:
Can you use the network locally?
If not then maybe the switch is the problem. You will ask then why don't you have to restart the switch? The answer to this is; if the switch is making trouble it can just corrupt the ARP table for the clients but the switch works fine, when you reboot the client the ARP table gets rebuild. How can you verify this? at a command prompt type:
arp -a
if anything is listed then type:
arp -d *
now test it, if the problem is gone then the problem is an ARP problem, which in most cases means that something is wrong with the Switch. The fact that ICMP (PING) works is no surprise to me, since I've seen before that a ping will work even with a corrupted ARP table.
Continued....

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