Just so nobody else wastes the amount of time I have recently please be aware that the transmission of data over USB 3.0 can cause radio frequency interference to 2.4Ghz WiFi rendering it useless.
I noticed that I couldn't connect my single-band (2.4Ghz) Motorola phone to the router and this set me on a wild goose chase having to contact the phone company, ISP, etc all within about 2 weeks.
I tried switching the router to 2.4Ghz (it also does 5Ghz) to see if I had a signal, tried individual SSIDs for each band, changing channels manually, etc, with no solution, but then I noticed on the router's GUI that there was 90% loading on 2.4Ghz with nothing connected!
I'd been running Jellyfin media server on Open Media Vault on a Raspberry Pi 4 with an SSD plugged into the USB 3.0 port. I did a bit of scouting around the net and found RFI on 2.4Ghz from USB 3.0 ports to be a common issue.
So, I plugged the SSD into the USB 2.0 port of the RPi 4 and hey presto RFi is begone. I can now use my phone on WiFi and everything is roses
I should have solved this sooner as I'd noticed a couple of months back that a wireless keyboard would only work with the RPi4 when the wireless dongle was plugged into the USB 2.0 port, it froze when plugged into USB 3.0.
USB 3.0 is a very difficult beast, and, as far as I'm aware, there are only proprietary silicon circuits you have to have licenses for as far as I know.
But how does the USB3.0 activity on your Raspberry influence the router or the phone? How close are the router and the raspberry? Have you tried different USB3.0 cables? Maybe you got a cheap un-shielded cable.
I'm asking because I'm using a Raspberry Pi 4 with a connected USB3 Ethernet adapter as well (short cable, rather stiff so likely properly shielded). My Raspberry Pi operates as WiFi hotspot at the same time and I have never had any single issue with this configuration.
I concur with DL6ER, a very large chunk of computer issues can be sourced to connectors or cables.
They usually are the most expensive parts of any piece of HW.
The Pi 4 was sat on top of the router, not ideal I know.
Standard USB-Sata cable employed but once the SSD was plugged into USB 2.0 the interference just went and I can see that it’s gone on the router’s GUI/spectrum display.
The RFI impacted only 2.4Ghz WiFi on the dual band router. My phone has only 2.4Ghz so couldn’t connect. It can now the issue is solved.
Like I said I had similar issues with the wifi keyboard freezing on the Pi4 when the wireless dongle was plugged into the USB 3.0 port. No issues with USB2.0 on said Pi.
This video helps to explain how USB3.0 impacts 2.4Ghz wifi.
