@AjayAPYour theory is wrong, in this case atleast.The line ALWAYS links at 2560Kbps/1024Kbps, even when speed is normal.Hence it is obvious that the speed is not capped by the modem, or anything remotely related to DSL like PPP.The cap is being done at the first hop, either through software (if the first hop is a PC acting as a gateway) or hardware. Most probably software because only then it can be modified using the Bandwidth on Demand script. If its not software, its VERY expensive hardware which is highly configurable like this.