Reposting full email report from South's BEST tech guy, by permission, some with some edits for clarity.
Report from South's BEST this past weekend concerning Wi-Fi interference issues.
The 1st day of the event was on Saturday Dec 5 2015, and there were reports of many intermittent VEXnet Wi-Fi link drops during the competition. After an hour or so, we decided to break out the game mode dongles. Testing in the Pit showed that when using the dongle we were able to achieve ~2x distance improvements between the joystick and controller before losing the VEXnet link so we went ahead and provided the game mode dongles to all of the teams competing on the field. There was definite improvement, however it didn't resolve all of the Wi-Fi interference issues. We used the game mode dongles on Sunday as well with even better results, however there were still a few intermittent VEXnet link drops.
Most of the Wi-Fi interference issues seemed to be caused by strong signals from both Auburn University's Wi-Fi networks and local hotspots that were setup by participants and spectators. Saturday was probably worse because the event took place at the same time as the SEC Football Championship game. Using Wi-Fi network analyzer apps on cell phones showed a large number of nearby strong transmitters on 2.4GHz channels 1, 6 and 11 with channel 1 being perhaps the least crowded (which is probably the main reason why the game mode dongle helped, since they force to channel 1).
We also did make several announcements during the competition asking people to shut down their hotspots. This probably helped quite a bit as well.
I want to note that this was certainly not a controlled experiment. We believe many of the VEXnet link drops were due to Wi-Fi interference, however there were most likely other things contributing to the problem such as overloaded motor banks, marginally charged batteries, loose connection between VEXnet Key and the Cortex Microcontroller, loose battery connection (those crappy white molex connectors), etc..
So the bottom line is that that game mode dongles did help, however they didn't resolve all of the issues. We are still very concerned about continued Wi-Fi interference issues in the future as the 2.4 GHz Wi-Fi spectrum seems to get significantly more crowded every year. We are grateful that you pointed out this game mode dongle to us as it definitely helped improve this year's competition!