bluetooth connection: host is down

I'm on ubuntu 17.10 and trying to connect my bluetooth headset QCY-Q19. it's able to pair but whenever I try to connect I get this error Connection Failed: blueman.bluez.errors.DBusFailedError: Host is down sometimes it connects for few seconds and then fails with the same error.

I've had this exact same issue before. What I ended up doing was unpairing the device, resetting it up, which solved the connection issue. After that, I saved it as a trusted device and so far haven't had issues since.

You may also see this error if the device you're trying to connect to is already paired to something else. For example, my headphones will latch onto my phone if it has Bluetooth on, causing my Ubuntu desktop to fail to connect.