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badconnection's avatar
New Contributor
4 years ago

Connection drop (difference between downstream channels power levels is more than 6dB)


My internet connection is not stable.

The downstream channels are divided in 2 groups: about 400MHz channels and about 800MHz channels.

The difference in power levels for these groups is more than 6dB.

I read that the difference in power between channels must be less than 3dB by DOCSIS 3 spec.

There are “Dynamic Range Window violation” warnings and “SYNC Timing Synchronization failure - Loss of Sync” messages in the modems log.

The test was done when the modem was connected directly to the service point and this power levels difference was still big 5dB.

I tried to chat with COX customer support to resolve my problem (Alex Silva).

The representative told me that they do not have equipment such as analyzers to confirm the signal quality at service point.

Also, it is a pity, but I couldn’t get any phone or e-mail to ask for further help.

Please can someone confirm that by DOCSIS spec the difference in power between downstream channels should be less 3dB?

Is it Ok if the difference in power for downstream channels is more than 6dB?

Maybe someone knows who can help to fix this connection problem?

My modem model is MB8600.

Thank you for any help.

1 Reply

  • Hi badconnection. This appears as if you may need someone to look into your account personally. We would definitely be able to assist you with this. Please reach out to us on Twitter at @CoxHelp via DM, visit us on Facebook via private message, or email us at Provide us the name on the account with the complete service address and the modem logs along with a link to this thread so we can get started. - Lisa, Cox Support Forums Moderator