I found this on the internet: https://www.intel.com/content/dam/www/public/us/en/documents/white- papers/usb3-frequency-interference-paper.pdf
When I pinged my router, I've seen some packets had a greater latency then others, so that could have been an interference. I couldn't test 5GHz as I don't have 5GHz with my router. I can't mesure voltage as I can't find vcgencmd for ubuntu. But I don't think I've heard any changes from my fan. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-raspi2 in Ubuntu. https://bugs.launchpad.net/bugs/1861338 Title: RPI4 wifi unreliable when usb3 storage is attached Status in linux-raspi2 package in Ubuntu: Incomplete Status in linux-raspi2 source package in Eoan: Incomplete Bug description: On RPI4, if you set up netplan to use wifi, and plug in a usb3 storage device to one of the 2x usb3 ports (the ones closest to the ethernet port), wifi will sudden stop working. If you unplug the usb stick while running a ping, it will usually start working again almost instantaneously. Kernel version I have is: 5.3.0-1017-raspi2 and I've confirmed this happens on both armhf and arm64 The only thing I found in journalctl that looks suspicious is this, but it seems to have happened before plugging in the usb stick: Jan 29 20:54:59 ubuntu wpa_supplicant[1129]: random: Cannot read from /dev/random: Resource temporarily unavailable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-raspi2/+bug/1861338/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp

