Hi Grumpycrab,
Thank for the trouble shooting steps tried and for the details description of the issue. This could be due to driver or card settings. I suggest that you flash BIOS to the latest version and update wireless driver. Click on the link below and enter the system service tag and click submit to get the drivers for your system model:
You may also change the Roaming Aggressiveness settings of the card and for information on this please visit the link provided below:
http://dell.to/10pz8WE
Revert for further assistance also provide the system model.
