Difference between Transceive​r Statistics vs. Speed tests

Question

We had been having problems with our DSL speed today.  We discovered (obviously) that most of the problem was that my son was watching Netflix on our TV (through an app directly on the tv, not through a game console), which was sucking up most of our bandwidth.
But, while testing things out, we checked our Transceiver Statistics.  We are getting about 3300 mbps download, but after running two different speed tests (speedtest.net and bandwidthplace.net), it seems we only ever really get about 1.5 - 1.6 mbps.  This was after turning off the Netflix stream, by the way.  This is basically our normal speed.
At any one time, we have 2 laptops and 2 Android phones connected to our network through a Beklin wireless router, as well as a desktop connected to the Belkin router through an ethernet cable.  The tests have been consisten regardless of the number of computers running at the time, as long as they aren't doing anything with a real network load.
I don't think it's a problem with the router, because we can copy files between the computers at about 4 megabytes per second (36 megabits per second).  Althought the WiFi connection says it's running at about 130 megabits per second.  Maybe that's an issue with disk speed, I don't know...
Anyway, is there anything weird going on, or is it a symptom of outside network load that our speed tests are roughly half the value we see on the Transceiver Statistics for the modem?
Here is the full details from our Westell modem Transciver Statistics:
Transceiver Revision: 7.1.254
Vendor ID Code:        4
Line Mode:               G.DMT-Mode
Data Path:               Interleaved
Transceiver Information
Down Stream Path
Up Stream Path
DSL Speed (Kbits/Sec)
3328
512
Margin (db)
7.0
12.0
Line Attenuation (db)
42.0
18.5
Transmit Power (db/Hz)
14.0
11.0
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Answer 1

The transceiver stats only measure the speed of the connection between your DSL Modem/Router and the Central Office Equipment. You can get the full 3mbs downlink speed with losses a lot higher than 42db   I have seen it above 60db and still providing 3mbps.
However the link between your modem and the Central office is only small part of the total path between your computer and whatever internet site you are connecting too. Speed tests measure end to end, as opposed to only a small part of the message path. As a result speed tests almost always show lower performance than transceiver stats.
The best analogy is Verizon effectively only provides the on and off ramps to the Internet Superhighway. Just because the local  ramp is clear is no assurance there aren't traffic jams elsewhere on the highway. The problem with most speed tests is you have no idea how your traffic was actually routed, and what constraints may be placed on it by parts of the network that Verizon has no control over.
The transceiver stats represent the best possible case. The reality is there is no shortage of issues upstream from the central office, either on, or off the Verizon network that can restrict your actual speed to considerably less than 3mbps. It is unlikely that your wiring inside the house is an issue, if it was, you would be seeing a downlink speed at less than 3mbps.
However your uplink speed seems slow. The nominal uplink for the 3mbps tier of DSL service is 768kbps, not 512kbps.