I am noticing continuous wifi disconnects when external HDD is plugged in a USB 3 port. Wifi seems to work fine when the same HDD is plugged in a USB 2 port...
This is probably due to the limited DMA addresses in 64-bit kernel. USB3 might use more DMA addresses than USB2.
Ok. I just wanted to point this out. I guess that it'll be fixed on the way... right?
It depends on the Raspberry Pi people. We use their kernel source.
That moving the device to the USB 2.0 port changes the behavior suggests that one possibility is that the USB 3.0 device may be generating interference in the 2.4GHz RF band, which could be causing the Wi-Fi disconnects.
Intel has a white paper on this issue here -> https://www.intel.com/content/www/us/en/products/docs/io/universal-serial-bus/usb3-frequency-interference-paper.html
If your wireless router supports the 5GHz band, switching to a 5GHz connection may help produce a different result when the HDD is connected via USB 3.0.