W5100 ethernet shield - can't upload sketches

[israelidanny]

I have a W5100 Ethernet Shield. When I connect it to my Arduino Mega 2560 I can't upload any sketches, or connect to the com port.

I do see the Arduino in the list of serial ports, but when I try to upload the sketch, I get the following errors:

Arduino: 1.8.4 (Mac OS X), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

Sketch uses 2326 bytes (0%) of program storage space. Maximum is 253952 bytes.
Global variables use 359 bytes (4%) of dynamic memory, leaving 7833 bytes for local variables. Maximum is 8192 bytes.
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
An error occurred while uploading the sketch

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Has anyone had to deal with something like this?

EDIT:
When searching the forum, I came across a hack for older versions of the shield:
http://mcukits.com/2009/04/06/arduino-ethernet-shield-mega-hack/

However, my shield has "MEGA compatible" written on it.

[Nick_Pyner]

How are you powering Arduino?
If you are repeatedly able to upload and communicate with just the bare Mega and only have a problem when you plug in the W5100 shield, it could be simply down to inadequate power. If you are powering just via a USB cable, try using a proper 9v 1A wall wart.

That ancient hack is just for even more ancient shields that don't have the ICSP pin cluster, and is nothing to do with your problem.

[israelidanny]

You're right - I am powering it only via USB. I'll give your suggestion a try. Thank you so much