[philso]

Theck your power and current return paths (it's not really a ground) for your CRio, your D-Link and it's power supply and your Digital Sidecar. Do a "pull test" on all crimps and terminals. We had a bad crimp on the power connections making a Victor behave very strangely.

Definitely see what happens with the direct ethernet connection and take the radio out of the equation. The commutators on the DC motors function as wideband noise generators and sometimes the noise ends up in the band that your radio is trying to work in.

Is your D-Link mounted on a metal plate? Sometimes, that can be beneficial and sometimes it can block the signal to the antenna. You can also try mounting the D-Link in a different orientation. The antenna performance was probably compromised to allow them to fit it inside the plastic box so it probably needs all the help it can get.

It is doubtful that the popping noise is the actual ESD. An ESD simulator, used for testing the immunity of industrial equipment, cranked all the way up only makes a soft crackle that is easily drowned out by the motors and other mechanical noises on your robot. It is more likely to be your relays cycling on and off or the PWM signals going to your motor controllers being corrupted and causing them to "change speed" suddenly making your motor(s) jitter.

Unless you have someone familiar with high frequency probing techniques available to help you look at noise with an oscilloscope, you may end up wasting a lot of time barking up the wrong tree.

Eric is correct that you can really mess up the power supply by indiscriminately adding capacitance to it. You would have to know how to use an oscilloscope well to check for this properly.