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change dsl mode on cisco 877 -Cisco and BT issue

hi all,

NB - I will need an idiots guide to this.

I have a new client who has a BT ADSL2+ installed with a Cisco 877 router. The router link is up and down like a yoyo - more down than up

I have come across this before with a draytek and it wsa due to the dsl modulation being set to auto as opposed to a specific adsl2+ modulation. That one needed to be set to ADSL2+ (Annex M) for example

if you can give me an idiots guide to this it would be really helpful. If you have any other ideas that would be great.

1 Solution
You need to check that you have this product part number:  CISCO877-M-K9 (or at least, that the product number of your router has an "M" in it).  If not, you won't be able to connect to a DSL line with Annex M operation mode.
Craig BeckCommented:
Cisco 877 routers have known issues with BT ADSL2 and 2+.  There is a bug in the firmware on these routers apparently.

I've installed lots of these in the past and never had any luck, however there appears to be a release of firmware which is stable with BT's 21CN... v4.0.195

If you have a SmartNET agreement you can download this from Cisco and copy it to the flash on the router.  When it reloads it will use the new firmware.

gareth629Author Commented:
Hi All,

thanks for your help, I ended up replacing the router with a Draytek which works a treat.

for completeness on an ADSL2 BT line the modulation needs to be G.DMT.

gareth629Author Commented:
Cisco and BT do not play well together.

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