Odd connectivity loss on reboot

[JDG1980]

I recently upgraded (sidegraded?) from a custom AMD FX system to a used Dell workstation with an E5-1650. This system is running Windows 7 Pro. Since the change, I've been having an unusual issue with my wireless connectivity (the location of the system makes Ethernet impractical as of now). Occasionally, when I cold boot or take the PC out of sleep mode, Windows fails to make a network connection upon logging in. The Wi-Fi icon shows the blue activity circle for a few moments, then fails and shows the yellow splat. Trying to manually connect to my router (which still shows up in the list of networks in range) results in a near immediate failure (fails in less than 5 seconds with an ambiguous error message). Rebooting again doesn't fix it; the only way I've found to do so is power-cycling the router. This issue affects both the standard and 5GHz networks. The Wi-Fi card is an Asus PCE-AC56, and the router is an Asus RT-AC68W with the latest AdvancedTomato firmware installed. I am inclined not to blame the hardware because this problem didn't happen on my old PC (with the same Wi-Fi card) and still doesn't seem to happen on my iPhone or Nexus tablet. But I'm not sure where to look next. Any thoughts?

 

[sdifox]

have you tried reinstalling driver?

 

[JDG1980]

have you tried reinstalling driver?

Yes. I originally used a generic Broadcom driver for the chipset, but when the problem cropped up, I switched to the newest Asus version of the driver on their website. Didn't help.