Hy

I had similar issues. I also thought about a broken device (bluetooth, wifi, usb-controller). I even bought a new pi…

The main issue was the power.

Since i built in my pi in a original NES-Case i screwed a power connector to the case and soldered a usb-cable to it. then i plugged the cable to the mausberry powerswitch and from there to the pi.

With this setup i had the same issues as you described above.

When using a 2Amp power supply and connecting it directly to the pi i managed to get it up and running stable.

good luck ;)