>         media: Ethernet 10baseT

> The led on the switch turns on indicating there's a link between the
> NIC and the switch, so I assume it's all ok.

That may be a dangerous assumption.  I've seen bad cables with one pair
OK and one pair bad show link in one direction but not the other (and
carry packets one way but not the other).  Presumably analogous
failures in a connector or the electronics close to the connector can
produce similar failure modes.

As for debugging it...most Ethernet cards have link lights of their
own; does it show link?  You also might try connecting directly to
another machine with a crossed cable and try tcpdump on the machines to
see if anything is getting through.

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