Internet Connection Dropping

[philb101]

I have a business client whose Internet connection is randomly dropping then reconnecting. I am not on site & attempting to diagnose remotely

The connection is ADSL & the ISPs status page shows no known faults at the moment.

The PC network is connected into a switch & through a SonicWall Firewall into the Router onto the ADSL line. since the Network stays up fine where would be the best place to investigate the problem

Is it more likely to be the Router than the SonicWall, remotely I can't log onto the Sonicwall or run a trace to the said IP

Any help would be appreciated

 

[Law]

Call the ISP first to verify their side is up and good. Then I would start first with the firewall. Then move onto the router then the ADSL line.

A few question to ask, did this problem just occur?

Did the business install any new hardware, software to the servers? Any configuration made? Do you have any server running like DNS, Proxy?

When the internet drop, on the client ping each other in the switch, if good then ping the firewall, if good then ping the router, if good then ping the ADSL line or IP (Usually the Public IP that you got). If good then ping a website. Start off like this until you get to the point where you don't get any response.

 

[philb101]

Thanks for the response
I spoke to the ISP & they recognised the line had been up & down, they suggested reseating all connections & they would test agian, possibly a BT fault After reseating line up again but just checked this morning & line is down
No the company have not had any new additons IT wise
When line drops the internal network remains ok

Will post again if cant resolve quickly

 

[Law]

Even though you can ping through the firewall to the router doesn't really mean that all connection is fine, you know what I'm saying? That just verify that the lower layer up to the network layer are fine, but the application layer may not be, because of the firewall. I'm just telling you this but if you think the firewall isn't the problem then OK I take your word for it since I'm not even there diagnosing the problem. How would I even know....

I guess the best way to see is try to access the router via the webbrowser from a computer that is behind the firewall. This should verify the entire layer is ok.


When you said the internal network is OK, I am assuming they are all connect to the switch or swithces connected to other switches. This is a good example of why you don't rely on the firewall, because in a switch environment all computer see each other via broadcast, they don't have to go through the firewall. That would mean they will work, but once they try to access some computer that is not part of their network they will have to go through that firewall.