intermittent dsl connection

[element19]

We have dsl for our dsl connection with a sonicwall firewall. The connection will go down for 2-5 minutes and then go back up again. I am connecting to the server remotely via vpn. When the internet goes down, I am able to ping the WAN ip address with no problem but but i am not able to ping the internal nat ip address. From the lan, we are able to logon to the firewall without a problem and everyone can still see each other on the network. Do you think its a hardware issue or some other network issue?

thanks for any response

 

[InnoTech]

i'm not understanding the post completely but from what i got was that:

1. you are connecting from outside the LAN
2. the LAN's internet goes down and the connection is lost.
3. once the connection is lost you can still ping the public (ISP assigned) IP address.
4. you're trying to ping a private (NAT ie. 192.168.XX.XX) IP address while trying to remotely connect.

if these are true:

1. make sure your firewall is set-up correctly for VPN conections.
2. once again, make sure your firewall is configured correctly. this is common with firewalls and broadband (DSL, Cable Internet)
3. if you can ping the public IP address when at a remote location, the internet connection isn't down. again i'd check the firewall or router settings.
4. you cannot ping any NAT or pritate IP address while not on that LAN.

once again if i didn't understand your post, i'm sorry. maybe you can give more info.

thanks

"Jack of all trades. Master of none."

 

[element19]

you're right. i am connecting from outside via vpn. When i cant connect to the remote lan, i'm still able to ping the public address but not the internal address.
Even though i can ping the public address, the people at the lan are also not able to get to the internet during this time.
From the lan, the people there can connect to the firewall when their internet is down...so i dont think its the firewall.
What makes it difficult to troubleshoot is that it goes down for a short time from 3-20 minutes 5x a day.
if it was the firewall configuration, wouldnt it not work at all?
I called my dsl and they said everything is up on their end.

 

[InnoTech]

well, for one thing i will have to disagree. we know that it will have to be either the firewall or the router. that's just a "no brainer". if you can ping the public IP then their link is there. for some reason thats unknown to us both is why its going down. to find out would be to reset the firewall next time it happens. if its not back up then reset the router.

you say they can connect to the firewall during this time and so can you. that alone would tell me that the firewall is the problem. just because its up don't mean its operating correctly. you could also try to take the firewall out of the picture and see how things go.

"Jack of all trades. Master of none."

 

[element19]

thanks for your help. i'll try to take the firewall out of the picture when this happens...which can be difficult because the connection will be back up by the time i get there.
I was also thinking maybe its some dos attack or some dns or broadcasting issue which i dont know how to troubleshoot.

 

[manarth]

element19 - if you're concerned about DoS attacks, etc, it's always worth having a read of your logs. Attacks normally stick out like a sore thumb!

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