I had the same problem with my MS Bluetooth Mouse 5000 that directly connects to my laptops internal Bluetooth Adapter 4.0. After a seemingly random time the mouse stop working despite being shown as connected in Bluetooth settings. I found that this seems to be related to the powersavings configuration. I use tlp (see first answer: info about tlp), and in
powertop I saw that all USB devices' powersaving options are enabled. The problem seems to be, that after the powersave option kicks in, the mouse won't reconnect anymore, so the core of the problem must be there.
However, this work-around worked for me now:
1.) I used
lsusb to determine the ID of my bluetooth device (I wonder why bluetooth counts as usb-device?):
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 003 Device 002: ID 041e:3042 Creative Technology, Ltd
Bus 003 Device 003: ID 8087:07da Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
This website helped me to identify which ID is bluetooth: identify USB IDs
In my case that was Bus 003 Device 003: ID 8087:07da Intel Corp.
2.) Then I used the ID: 8087:07da to blacklist the power saving option in tlp:
Open the tlp configuration file using the terminal:
gksu gedit /etc/default/tlp
and search the line containing: USB_BLACKLIST=
Then edit this line and enter the ID of the bluetooth device, e.g. in my case:
After restart, the Bluetooth my did not disconnect anymore and in
powertop, Tunables I see that powersave options for this ID are disabled.