Attenuation changes between 2 values

The downstream line attenuation on my Netgear DG834GT is either 15.0 db or 46.0 db, but never anything in between. Most of the time it is 46, but seems to spend the odd 10 mins or so at 15.

Does anyone know why this is? Is it a 'feature' of the router, just how MAX ADSL is implemented, or indicative of unusual conditions on my line? It is not causing any problems it's just that a) I'm the curious type and b) I work in telecomms so it's interesting in a geeky sort of way.

Cheers, Steve.

The 'occasional 15db attenuation' is a bug of the router's chipset, I think a few other routers have it sometimes, can't remember which chipset they are using.
But its nothing to do with your line. Usually a resync of the router should do it

Ah yes, many thanks.

It's the BCM6348 chipset.

You would have thought Netgear would have got round to patching that by now (they have patched other non-critical bugs in the previous 3-4 firmware updates).

Probably the same reason why the router sometimes reports a zero SNR via 3rd party diagnostic utilities.