Thank you for your work) 
The keyboard is http://www.samsung.com/us/support/owners/product/BKB-10USWEGXAR
Once it is paired it just becomes unstable. Big latency, and also Bbbuuuuugs liiike thisss. That particular bug is making it unusable. Also i was checking it in kacpimon, if acpi sees several key presses also, and it does. While that laggs there are no any errors at all in syslog or dmesg, only after disconnect. And it is not disconnected right after pairing. It is very random, but sometimes before error about disconnect drm:intel_pipe_update_end [i915] bug appears, sometimes not. Also important to mention that with windows 10 it works perfectcly (fast, stable, no disconnects). Every Bluez install i was installing with bluetooth library, but now i will try to work with native 5.37 lib and old and stable bluez to find if it is bluez or lib bug. A bit later i will give you my logs with buggy and with stable bluez. syslog with disconnect after intel error:
Jun 28 14:07:03 leonid-Lenovo-G500 kernel: [ 2630.762724] [drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe A (start=154570 end=154571) time 116 us, min 763, max 767, scanline start 762, end 768
Jun 28 14:08:26 leonid-Lenovo-G500 dbus[676]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service'
Jun 28 14:08:26 leonid-Lenovo-G500 systemd[1]: Starting Hostname Service...
Jun 28 14:08:26 leonid-Lenovo-G500 dbus[676]: [system] Successfully activated service 'org.freedesktop.hostname1'
Jun 28 14:08:26 leonid-Lenovo-G500 systemd[1]: Started Hostname Service.
Jun 28 14:08:26 leonid-Lenovo-G500 org.gtk.vfs.Daemon[1159]: ** (process:30582): WARNING **: Couldn't create directory monitor on smb://x-gnome-default-workgroup/. Error: Operation not supported by backend
Jun 28 14:09:10 leonid-Lenovo-G500 gnome-session[1294]: Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
Jun 28 14:09:15 leonid-Lenovo-G500 org.gnome.zeitgeist.SimpleIndexer[1159]: ** (zeitgeist-fts:2368): WARNING **: Unable to get info on application://nautilus-autostart.desktop
Jun 28 14:09:58 leonid-Lenovo-G500 URfkill[667]: device_changed_cb: ideapad_bluetooth
Jun 28 14:09:58 leonid-Lenovo-G500 systemd[1]: Starting Load/Save RF Kill Switch Status...
Jun 28 14:09:58 leonid-Lenovo-G500 systemd[1]: Started Load/Save RF Kill Switch Status.
Jun 28 14:09:58 leonid-Lenovo-G500 kernel: [ 2805.143113] usb 1-1.3: USB disconnect, device number 4
Jun 28 14:09:58 leonid-Lenovo-G500 acpid: input device has been disconnected, fd 17
Jun 28 14:09:58 leonid-Lenovo-G500 bluetoothd[880]: (bluetoothd:880): GLib-CRITICAL **: Source ID 144 was not found when attempting to remove it
Jun 28 14:09:58 leonid-Lenovo-G500 URfkill[667]: device_changed_cb: hci0
Jun 28 14:09:58 leonid-Lenovo-G500 bluetoothd[880]: Endpoint unregistered: sender=:1.61 path=/MediaEndpoint/A2DPSource
Jun 28 14:09:58 leonid-Lenovo-G500 systemd-rfkill[1271]: Failed to open device: No such device
Jun 28 14:09:58 leonid-Lenovo-G500 bluetoothd[880]: Endpoint unregistered: sender=:1.61 path=/MediaEndpoint/A2DPSink
Jun 28 14:09:58 leonid-Lenovo-G500 URfkill[667]: removing killswitch idx 5 hci0
Jun 28 14:09:58 leonid-Lenovo-G500 systemd[1]: bluetooth.target: Unit not needed anymore. Stopping.
Jun 28 14:09:58 leonid-Lenovo-G500 systemd[1]: Stopped target Bluetooth.
Jun 28 14:11:22 leonid-Lenovo-G500 kernel: [ 2889.790543] [drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe A (start=170069 end=170070) time 189 us, min 763, max 767, scanline start 762, end 769
Jun 28 14:11:32 leonid-Lenovo-G500 dbus-daemon[1088]: Reloaded configuration
Jun 28 14:11:32 leonid-Lenovo-G500 dbus-daemon[1088]: Reloaded configuration
Jun 28 14:11:32 leonid-Lenovo-G500 dbus[676]: [system] Reloaded configuration
Jun 28 14:11:32 leonid-Lenovo-G500 dbus[676]: [system] Reloaded configuration
Jun 28 14:11:40 leonid-Lenovo-G500 URfkill[667]: device_changed_cb: ideapad_bluetooth
Jun 28 14:11:40 leonid-Lenovo-G500 systemd[1]: Starting Load/Save RF Kill Switch Status...
Jun 28 14:11:40 leonid-Lenovo-G500 systemd-udevd[316]: specified group 'phablet' unknown
Jun 28 14:11:40 leonid-Lenovo-G500 systemd[1]: Started Load/Save RF Kill Switch Status.
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.206967] usb 1-1.3: new full-speed USB device number 6 using ehci-pci
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.289353] usb 1-1.3: New USB device found, idVendor=105b, idProduct=e065
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.289357] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.289359] usb 1-1.3: Product: BCM43142A0
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.289360] usb 1-1.3: Manufacturer: Broadcom Corp
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.289362] usb 1-1.3: SerialNumber: F82FA8ED4D02
Jun 28 14:11:40 leonid-Lenovo-G500 URfkill[667]: adding killswitch type 2 idx 6 soft 0 hard 0
Jun 28 14:11:40 leonid-Lenovo-G500 URfkill[667]: Setting device 6 (BLUETOOTH) to unblocked
Jun 28 14:11:40 leonid-Lenovo-G500 URfkill[667]: set_soft: Setting BLUETOOTH to unblocked
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.298247] Bluetooth: hci0: BCM: chip id 70
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.314254] Bluetooth: hci0: leonid-Lenovo-G500
Jun 28 14:11:40 leonid-Lenovo-G500 kernel: [ 2907.314259] Bluetooth: hci0: BCM (001.001.011) build 0312
Jun 28 14:11:40 leonid-Lenovo-G500 mtp-probe: checking bus 1, device 6: "/sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3"
Jun 28 14:11:41 leonid-Lenovo-G500 mtp-probe: bus: 1, device: 6 was not an MTP device
Jun 28 14:11:44 leonid-Lenovo-G500 kernel: [ 2910.902369] Bluetooth: hci0: BCM (001.001.011) build 0312
Jun 28 14:11:44 leonid-Lenovo-G500 kernel: [ 2910.918324] Bluetooth: hci0: Broadcom Bluetooth Device (43142)
Jun 28 14:11:44 leonid-Lenovo-G500 systemd[1]: Reached target Bluetooth.
Jun 28 14:11:44 leonid-Lenovo-G500 bluetoothd[880]: Endpoint registered: sender=:1.61 path=/MediaEndpoint/A2DPSource
Jun 28 14:11:44 leonid-Lenovo-G500 bluetoothd[880]: Endpoint registered: sender=:1.61 path=/MediaEndpoint/A2DPSink
Jun 28 14:12:03 leonid-Lenovo-G500 kernel: [ 2930.529932] hid-generic 0005:04E8:7021.0007: unknown main item tag 0x0
Jun 28 14:12:03 leonid-Lenovo-G500 kernel: [ 2930.532096] input: Samsung Bluetooth Keyboard BKB-10 as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3:1.0/bluetooth/hci0/hci0:11/0005:04E8:7021.0007/input/input19
Jun 28 14:12:03 leonid-Lenovo-G500 kernel: [ 2930.534024] hid-generic 0005:04E8:7021.0007: input,hidraw2: BLUETOOTH HID v7.00 Keyboard [Samsung Bluetooth Keyboard BKB-10] on f8:2f:a8:ed:4d:02
Jun 28 14:12:03 leonid-Lenovo-G500 upowerd[1391]: (upowerd:1391): UPower-Linux-WARNING **: treating change event as add on /sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3:1.0/bluetooth/hci0/hci0:11/0005:04E8:7021.0007/power_supply/hid-90:7f:61:10:3c:ab-battery