Multi-problem solution found . . . in the likeliest/unlikeliest place (choose one)
For the past couple of weeks our LAN has been experiencing a variety of inconsistent, episodic problems, about which I have posted herein, and on which several TeeEssers have generously offered sage advice. These problems ultimately affected printing, on-line connections, mail in/out, etc. etc. apparently even iChatting/iSighting, on 3 different computers (iMacIntel, iMac G-6; AluminumPB) each running an apparently well-maintained 10.4.9
Over the last 36 hours, the problems became near-totally debilitating, so that I called AppleCare 3 times - primarily on why our 3-month old Apple Extreme Base Station would not maintain proper settings for our LAN. Finally, I was told to take it to the Genius Bar @ the Burlingame Apple Store, for testing and possible replacement.
Over 90 minutes or so, The Resident Genius there tried to break it. No luck: reconfigured twice - no problem; connected to the Apple network no problem; downloaded a BIG file - no problem. So back home “we” came. I decided it was clean-up time of the physical desktop, hereabouts. I have been checking connections so often in the past 10 days that both equipment and cables were, well, askew.
Everything's clean and neat, now. Cables labeled, coiled etc. etc. Oh yes, the connectors on the 18" ethernet cable between the Comcast modem and the AEBS seemed not to fit as snugly as the other jacks of various sorts. It has those rubberized doohickeys (technical term) covering the tangs on the jacks). Losing pliability (I surmise) meant that the tang was not “permitted always to fully seat itself in the port. Bingo!
Before you say anything . . .
“Of course, I checked the cables several times during this ordeal. What I didn’t do was check to see that apparent snugness-of-fit was accompanied by the “click” of the jack-in-the-port” So, however/whatever the combination of factors in the Base Station's connection to the cable modem, they apparently produced a deterioration in router (and LAN) effectiveness that messed over most everything else
I really do thank everyone for their valuable effort and suggestions.