We are able to establish a working VexNet link for about 5 seconds then connection is lost and the joystick just flashes a red light for the VexNet light. So, its not that it won’t establish a link, but it wont keep the link.
Does it work correctly with the USB A-A Cable??
Check your VEXnet key placement to make sure it isn’t buried in a bunch of metal.
Check your battery connection by turning on the Cortex (don’t need the joystick) and wiggling the battery connection around to check if it’s loose. Use pliers to fix male/female heads if needed.
Check with a clean set of VEXnet keys if you have them.
If you find that you have problematic VEXnet keys, you should be able to send them back to VEX for repair.
Have you worked through the flow chart on the Vexnet User Guide (p. 10)?
I know exactly what happened to you, because this happened to both of our VEX robots. The fix is easy. You need to run the VEX firmware update on BOTH your “Cortex” AND your “Joystick”. We connected the USB to the Cortex and ran the firmware upgrade utility but didn’t realize we had to do the same thing with our “Joystick” controller.
Let me know if that helped.