ust bought new Mac Mini with M1 chip and intermittently mmy bluetoth devices intermittently disconnecting!! Help

Poorly shielded USB cables and devices can cause both Wi-Fi and Bluetooth issues.

see > https://support.apple.com/en-us/HT201542

New here, so I am not sure my reply to the Email works.

Magic Keyboard no issues.

Magic Mouse - on & off

HDMI Video Cable (4K HDMI Cable 1 Pack 6ft, JSAUX 18Gbps High Speed HDMI 2.0 Braided HDMI Cord)

Not using any USB. WiFi works with previous iMac & MacBook in same location with full strength indication.

I'm struggling with this problem for months. I noticed that high quality display cables can reduce the problem; high quality usb-c cables can reduce the problem; a more recent display (better shielded display?) can reduce the problem; an old BT mouse vs a BT 5.0 mouse works better. But the problem doesn't disappear at all.

I'm the hoping that each new release of Big Sur is going to solve. But it hasn't yet happened. Maybe the forthcoming version oo Mac OS, Mac OS 12 "Monterey", might solve it.

I have no truth in my hands about this problem but in my experience, as already said, depends from many thing. As like you I have my Magic Keyboard (with touch ID) working and my Logitech ten - years old (minimun) mouse having problems. Before changing the display's HDMI cable with the actual, the actual Magic Keyboard was connecting and disconnecting every 2-3 seconds.

But this was not happening with the previous Magic Keyboard (grey model) without the touch ID. Today I got a new mouse (can't remeber the brand) wich is surely a BT 5.0 mouse. Absolutely unusable! So? It's a nightmare.

I'm hoping a minor release of Big Sur is going to patch the problem because I dont' want to upgrade anymore to further OSes although is not a good practice to keep the first release of an OS that came with the machine you own (in this case, Big Sur with M1 machines). IMHO.

I don't use USB devices and my Mac mini intermittently drops and re-connects after a short period.

What drops and reconnects?

A poorly shielded display cable, can have the same effect as USB 3.0 and USB-C cables.

I guess I have to manage it if I want to use the mouse, why only the mouse & not the keyboard? Used an old PC USB mouse w/o issue, so for now that is my solution.

I will w/o fail review relevant upgrades b4 opting to upgrade and never really had any issues with most OSs, including early Vaxs, HPs, Primes, CDC, …)