Digital Wild West

My D-Link DSL-604+ has been plodding merrily along for 4 years now.

In that sturdy service it has suffered three heart-stopping incidents.

1. Design Bug

During the teething stage all those distant years ago the only - and humongous - hangup was that it would stop after a few days.

Forum hunting and D-Link support-hassling eventually uncovered the truth: disable the Proxy DNS which filled up and overflowed all over the computer desk.

Resets were emptying it so for a few more days it would run, then crash. There might have been a firmware fix - I had already done one - but upgrading firmware in a consumer plastic box is no fun at all, and less so for the faint-hearted.

Workarounds are good a fix as any.

2. User Confusion

A year ago it stopped. After the traditional poking, tapping, and thumping, I did the only thing a techno-literate ape can, and gave ‘er the old "DC reset" as we call it. Power off. Count to 5. Power on.

Counting to five is an ingrained habit born of blowing up switched-mode power supplies - those things that collect dust inside your PC whilst supplying juice to keep the little silicon creatures warm. Dust obligingly supplied by those noisy bloody fans.

You see, a quick off/on for a power supply of this type can make it expire from confusion, often with a loud pop, due to voltage surges of an unpremeditated design/engineering kind. Bitterly-acquired experience, btw.

But I digress. The D-Link kept disconnecting from the Internet. So I discovered removing the power (that little DC plug in the back supplied by a plugpack, as so many things are in the home nowadays) and reconnecting it (the only way to switch it off and on) would resume service.

Away it would go for a day or three … and off again.

While wondering how long I might tolerate this, fortune smiled. SWMBO (She Who Must Be Obeyed) was at her PC next to me and - calling it a day - did that little trick I taught her: Right-click Local Area Network -> Disable.

Except she introduced a variant. Right-click Internet Connection -> Disable. Down went my Internet, my FTP, my email … my life!!

Yes dear reader, I saw the connection between these two disparate events. Her disconnecting the D-Link 604 from the Internet remotely, and me suddenly unable to work.

And hey! I nearly missed it! Could have gone on for months this way and eventually thrown out the D-Link only to find the replacement doing likewise!

How many households are afflicted in this way we shall never know.

Watch for it!

3. Tangle-footed

T’other day incident three loomed as a brief dropout in the form of "Local Area Connection. A network cable is unplugged"

No it ain’t, I protested. So it reconnected and carried on.

More of these incidents troubled me. Thoroughly checking the D-Link and trawling through its configuration screens, and finally the Line Condition and Carrier Chart screens, revealed nothing.

Phoning a support ticket to the ISP about service dropouts - that might be the ‘modem’ but equally likely the copper (phone line) - generated the response:  "foreign battery detected on the line" (referring to unwanted or unexplained DC [direct current]) which they would pursue and correct. Typically this is caused by copper faults, leakages, resistance, short circuits, whatnot.

Despite the serious-sounding fault, the phone and Internet were reliable except for occasional dropouts as described.

Days later, awaiting the Telstra tech’s purposeful investigation and endless postponements due to ‘inclement weather,’ SWMBO called me to report a total outage. No amount of tutoring on how to ‘DC reset’ the thing produced the desired result I once-confidently expected.

Puzzling. This was indeed an outage. Had the copper gone totally AWOL? Still, the phone was working. Had the line tech upset the modem or disabled the service?

Arriving home that evening I rushed into the office and tried the ultimate trick myself. Nup. Nothing. And worse, both PCs had ‘no cable’ messages and hers also reported "IP Conflict" - not what I expect from a DHCP (automatic assignment of Internet protocol addresses by the router).

The plot thickened when I powered the D-Link 604+ off/on several times and still no change. Even waited a minute, several times. "Cable disconnected" still reported by all PCs.

The fog cleared a little when my notebook PC found the Internet by wireless. So, it’s the Ethernet switch component of the D-Link (used for cabled network connections) that’s lost the plot.

Only when I followed the Prime Directive of PC repair - "Dissemble till it starts working" - and removed the Ethernet cables from the router’s inbuilt switch did it revive.  Reconnecting my desktop PC as the only computer - to eliminate any other PC ‘bringing it down’ - found it back to normal.

And it continued normally till now with all PCs back online.

There is no explaining such behaviour. Systems of powered electronics often need their components totally isolated to allow interconnecting ports to ‘relax’ electrically when a lockup occurs. Those little silicon junctions in almighty arrays of untold complexity can often become stuck in sustained and unwanted patterns that might take hours or days to leak back to zero volts if circuits are maintained.

Ultimately this is likely a software bug, in the absence of a hardware fault. Software always has bugs, and software controls hardware absolutely in today’s technology.

So my theory goes, an unforeseen combination of voltages created by either random signaling from the router component, or by subtle surges from the computer via their NICs (Network Interface Connectors), tripped up the circuitry in the Ethernet switch component and was maintained by power from the PCs despite removal of local power.

One more failed ‘reset’ and it would have been junked. That close. That subtle.  

Today’s tip concerns broadband Internet (aka DSL, ADSL) not working despite the computer, the modem, the phone line (DSL over copper) AND even the house being new!

The symptom?

I plugged it all but there’s no connection. In fact, when I plug the broadband modem in, I lose dial tone. And yep, I checked filter placement, even tried another filter.

Seems an open and shut case at first. Must be the the service provider (ISP). But, no, they claim it’s ready and waiting.

Next suspect is the modem, a new one supplied with the computer. Suggested another be swapped in to at least remove that from the list. In fact, experience suggests you should have a spare anyway for that inevitable time when the service stops and the ISP tells you there’s nothing wrong at their end. If you can afford fast Internet and a PC then you can afford to be somewhat self-reliant with not only knowledge but equipment.

Bring your computer and the modem to our workshop and we will at least confirm they talk and that your provider’s details are correctly entered.

He did and we did. The problem? Quite a few, actually.

1. The "modem" was a "broadband wireless router" less the modem! From a leading vendor like Dell one would wish such a vendor would stamp "gotchas" all over this ever-so-common area of confusion amongst non-cognoscenti. One needs a modem FIRST. A modem plus router is BETTER. A modem plus router plus WIRELESS is nicer, too. They can be in separate plastic boxes for separate purchase. Unless you have the MODEM part, you cannot connect to the Internet.
   
2. The ISP was a slack tart. They provided a username and login but NOT the type of service.  Our victim was never going to hit  the Internet unless he could tell the modem/router what flavor of protocol!! [PPPoE, PPPoA, etc.] This needs to be entered in the ‘modem’ department via the next step. This wonderful ISP emailed the information to its victim - the information he needed in order to connect and collect the email (sigh!).
   
3. Our hapless friend did figure, from careful reading of the router’s brochure, how to ‘browse’ into the web page living inside the little plastic box (that he believed was a modem) by entering a "web address" in the typical form http://192.168.1.1 or similar into his browser. Note, I’ll repeat, the plastic box has a website inside it. Web pages do not have to be on the web. A simple idea that most people find hard to get their brain around at first.
   
4. The web page allows configuration of the modem so it can connect to your ISP and supply the magic words "Connected" - our friend saw only "Not Connected." He knew something was up!

I could write a novel on this but suffice it here to say that this is the most common, even notorious, reason people who have just purchased a new computer with "broadband" routers cannot make it happen. The vendors simply do not care that you don’t know the difference between "routers" or "switches" or "modems."

It has the magic word "Broadband" so you naturally assume it’s the goods. Who wouldn’t.

PS: One other common scenario where, perhaps, one loses dial tone when the broadband "modem" is connected - and normal phone operation when it is disconnected - is after an electrical surge (typically lightning, or a nearby electrical storm) has "fried" your modem’s input.

The phone could survive, or not, of course.  Either way, you become obsessed over the loss of Internet and blind to the obvious. In both cases (wrong new device, or faulty old device) the input socket electronics - either damaged or electrically mismatched - places an incompatible load across the phone line. "Impedance" is a term describing the signal loading on a circuit. A "dead short" is another term, suggesting too-low an impedance while "open circuit" means too high :0)

Either case will prevent a circuit (that’s your home and the phone exchange and the copper/cable connecting them) from operating. It’s the "short circuit" that cripples the circuit when the cooked modem, or "Ethernet router" (not modem) is placed across the phone line.

Lesson to take away? Look for the magic word "modem" when buying for an Internet connection. The word "modem" is well known from dialup days and derives from the original box designed to convert a phone signal to digital-speak for computers.

Think: "Is it a modem? Or does it have a modem in it?"