Cannot connect to BLE device on Raspberry Pi

Question

I'm trying to connect to a BLE device (Heart rate sensor, Polar H7), on a Raspberry Pi 2. I use the last version of bluez (5.35) found here: http://www.bluez.org/download/ But when I'm trying to connect using gatttool, I always have "connection refused" error.

Here is what I do :

pi@raspberrypi ~ $ sudo su
root@raspberrypi:/home/pi# hciconfig dev
hci0:   Type: BR/EDR  Bus: USB
        BD Address: 5C:F3:70:69:54:3D  ACL MTU: 1021:8 SCO MTU: 64:1
        DOWN
        RX bytes:616 acl:0 sco:0 events:34 errors:0
        TX bytes:380 acl:0 sco:0 commands:34 errors:0

root@raspberrypi:/home/pi# hciconfig dev up
root@raspberrypi:/home/pi# hcitool lescan
LE Scan ...
00:22:D0:6D:E0:E6 (unknown)
00:22:D0:6D:E0:E6 Polar H7 6DE0E61C
^Croot@raspberrypi:/home/pi# hcitool lecc 00:22:D0:6D:E0:E6
Connection handle 64
root@raspberrypi:/home/pi# gatttool -b 00:22:D0:6D:E0:E6 -I
[00:22:D0:6D:E0:E6][LE]> connect
Attempting to connect to 00:22:D0:6D:E0:E6
Error connect: Connection refused (111)
[00:22:D0:6D:E0:E6][LE]> 

I tried to follow this topic: BLE gatttool cannot connect even though device is discoverable with hcitool lescan but it did not work for me.

Answer 1

I had to disable the plugin pnat in /etc/bluetooth/main.conf -> DisablePlugins=pnat. I read that it's unstable, but I don't know much about this plugin.