I am having trouble communicating with my Mega2560 + ethernet shield when not going through a router.
Some computers can identify the need to use a crossover cable and will do the "crossover" internally on a one to one cable - doesn't work!
Seems that there are two types of crossover cable - 2 pair and 4 pair crossover (T568B)
1 - 3
2 - 6
3 - 1
4 - 7
5 - 8
6 - 2
7 - 4
8 - 5 .......doesn't work!
and
1 - 3
2 - 6
3 - 1
4 - 4
5 - 5
6 - 2
7 - 7
8 - 8 .......doesn't work!