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New Member

Disconnects from ADSL Line

Hi there.

We have a Cisco 1801 which we have only just bought. It works well for a few minutes and the CD light comes on, then it decides that it has lost connection, and resynchs to the line. Sometimes this works and the connection comes back up, other times it sits there for a few minutes before it will reconnect. When it's reconnected, sometimes it stays connected for a few minutes other times it only connects for a few seconds.

When it does synchronize, it does at about 5mbps, when other modems only connect at 3.5mbps, so it seems like it's connecting too fast.

Other modems work fine.

Do I need to set the noise margin in the modem somewhere because I cannot find how to set this.

Any advice appreciated?


Hall of Fame Super Gold

Re: Disconnects from ADSL Line


Which IOS is on your 1801? Do you have access to CCO download to try a latest image? There isn't much you can do to configure ADSL at L1 level.

New Member

Re: Disconnects from ADSL Line

Hi there.

It's running IOS V 12.4(6)T6, with SDM version 2.3.1

We don't have access to CCO download unfortunately.

Hopefully that helps, but as I can see we've got all the latest images, etc, anyway.

We had another one go back with the same fault and were told it was a faulty router, but it seems unusual to have two with the same fault.

Hope you can help!

Hall of Fame Super Gold

Re: Disconnects from ADSL Line

I suggest you get a support contract for the router and advise the TAC. Try to collect at much data as possible like what DSLAM chipset the ISP is using. They may have precise data for situations in your country too.

Hope this helps, if it does, please rate it!

New Member

Re: Disconnects from ADSL Line

Well, you don't blame Cisco for this. I strongly suggest you check your line stats like SNR Margin, Line Attenuation and Loss of Frames. Low SNR Margin or high attenuation can cause of sync and unsync problem.

You may need to decrease your line speed to check sync un-sync problems.