It can’t be that as it happens every time, regardless of device, be it an external HDD, my iPhone, my Magic keyboard or anything else - and it literally never happened on High Sierra or anything else before that.It’s radio interference. Try repositioning the USB devices.
I'm not having the same issue, but my WiFi has been flakey ever since upgrading to HS. Up until a month or so ago bluetooth would just turn off, then turn back on in 15-30 seconds. Many times I had the bluetooth preference pane open I would see this. My mouse and keyboard with then reconnect. I started keeping my magic keyboard plugged in all the time so I could do something. Occasionally my mouse would not connect and I would have to reboot.
Except that I have a similar issue on my 21" 2017 iMac using the wireless keyboard and Magic Mouse that came with it. Bluetooth will suddenly crap out, rendering both devices unresponsive, and then come back around 30 seconds later. Happens more or less daily. There's definitely something wonky about Bluetooth in Mojave...mj not Apple's responsibility. Get over to Logitech and tell them to get their fingers out and come up with a driver for your mouse.
How is it not Apple's responsibility ifmj not Apple's responsibility.
Page 4 of this thread on Mac Mini sub forum is interesting and might be related as all 2018 Minis come with Mojave by default.