Hello,
I started a project with arduino mega 2560 + ethernet shield r3 (5100).
I can read/write to the sdcard on the shield so i guess no problem with SPI. but all exemples are failling with ethernet.
I tried pinMode(53, OUTPUT), and i still have the same result.
I tested the ethernet shield on an arduino UNO, and it's working properly.
I read a lot of topics here and there, but never find a solution. I guess I'm not the only one with this issue.
some time ago I've written a sketch for an UNO which uses SD and Ethernet at the same time and I tried this also for the MEGA now and imho it works:
It is just a small data logger which
writes data to the SD Card,
a NTP client to get the current time (for logging)
and webserver to download the data from the SD Card: