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.