I notice that my router also gets kicked when the BBB shuts down. If I don’t connect the BBB directly to the router/modem, but instead I route it through either the ethernet or the USB of my laptop (which then connects to the router via wifi), then the router doesn’t get kicked. I’m starting to wonder whether the BBB’s ethernet connector is generating some electrical noise that bothers the router/modem when connected directly.
Have a couple of dumb questions:
- did you get a chance to try a different “optimal length known good quality” CAT5/CAT6" cable ? Or
- a different ETH port on the router/modem ?
One option may be to use an inexpensive good $20 switch/router in the middle.
Dunno if it is cost effective to use a network-tap or sniffer device to root-cause this 
/venkat
Those are all great questions! Now that you suggested it, I tried three known-good cables and three different router ports. Still no luck. I can borrow a netgear gigabit switch (but not today), and I imagine that should work at least as well as my laptop kludge. I’m just testing this BBB out for a friend, and I don’t suppose he’ll have the same issue with a different router/modem.
Thankyou for your help!
If possible, you may want to try this:
-
get a known working eth hub (not switch),
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get a known working switch,
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wire them up as shown in the (ASCII image of) article below:
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follow the applicable steps in Part I / II (skipping the $$$ network-tap part), or
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follow the steps in using wireshark, as in:
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http://wiki.wireshark.org/CaptureSetup/Ethernet#Capture_using_a_network_tap
Cumbersome steps, no doubt, but may be able to get further down the debug road. The only other variable you did not test, is the ADSL modem itself. If that test fails too, an RMA of the BBB is the last option, I think. Other than using an expensive tap, you would’ve tested all possible variables…
/venkat