I was assuming the poster was located in the U.K. since he stated he was using Demon HomeOffice 8000.
I was under the impression this WAS a reasonably technically orientated forum. My mistake...
BT = British Telecommunications. One of the main telecoms providers in the U.K.
Master or Master Socket = Main telephone socket within customer's premises that connects to the wires coming from the telephone exchange. "Master" is used to distinguish it from a "Secondary" socket which doesn't have bell capacitor, spark gap or bleed resistor circuitry inside.
NTE5 = A specific type of Master socket fitted by telecoms companies (BT included), which if wired correctly, enables the customer to disconnect all extension telephone wiring within the premises, when the lower half of the faceplate is unscrewed and pulled out. This is very useful when trying to identify where faults are likely to be located.
Router Line Stats = Most routers provide statistics relating to the ADSL (Broadband) line between the exchange and customer's premises. These statistics will give, amongst others, SNR Margin (Signal-to-Noise Ratio) and ATTN (Loop Attenuation figures. These figures are useful in establishing how capable the line is for carrying a Broadband signal, and if that signal is likely to provide a solid Internet connection. E.g. If you said your DS SNR Margin was 4dB, your DS ATTN 63dB, and you had a 1Mbps circuit provided, I could immediately tell you that you'd probably not have a stable connection, if indeed you'd got one at all!!
RJ11 = Descriptive reference to the small (normally clear plastic) telephone jack used to connect the router to the ADSL microfilter. How else to describe it without waffling on for three or four sentences??
With a normal USB modem or router installation in the U.K., the customer will be provided with a lead to connect the modem or router to the telephone line. This lead will have RJ11 connectors on BOTH ends. One end fits into the modem or router, the other end must be fitted into the relevant socket on the ADSL microfilter. If we go back a few years to the time when good ol' fashioned dialup modems were the only way for most folks to connect to the Internet, the lead we used had an RJ11 at the modem end and a conventional telephone plug (commonly known as an LJU) at the other end. No filters were required, and the lead was plugged directly into a convenient phone socket.
Now, if the poster was concerned about a possible problem with any of his ADSL microfilters, what I was suggesting was to use one of these old modem leads which could be directly plugged into the Master socket thereby eliminating the need for a filter. On an ADSL enabled line, the filter is only needed for telephone handsets, fax machine, burglar alarm circuits, Sky boxes etc. You DON'T need a filter for a modem or router.
Does that make it any clearer?
ROGER - G0AOZ.