Hi ORAC, and thanks for the thoughts. This particular Aztech modem uses a regular plain old ethernet cable, the non-crossover type. Even so, in trying to sort this mess out, I did try using one, but no luck.
As I described earlier, I can connect no problem with both the desktop PC and the 5200 laptop to the router no problem (as long as I plug them into the "OUT" ports with the Aztech plugged ALSO into an "out" port on the Router...and still no success connecting for the 2410 Laptop.
I'm still stumped.
Any other suggestions, please?
Networking? Try tin cans and a string....
