cannot renew IPV6 address

[Jean-Max Reymond]

Hi,
I am running dhclient 4.3.5 (from isc site) on ubuntu 16.04 LTS
When starting my server, all is OK, I have an IPV6 address, I can ping, 
ssh, etc.
After 12 hours, the interface is down and I cannot obtain a new IPV6 adress.

# cat /etc/dhcp/dhclient6.conf
interface "eno1" {
    send dhcp6.client-id 00:03:00:01:73:41:e0:29:71:a3;
}

$ /usr/local/sbin/dhclient -cf /etc/dhcp/dhclient6.conf -6 -P -v eno1
Internet Systems Consortium DHCP Client 4.3.5
Copyright 2004-2016 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on Socket/eno1
Sending on   Socket/eno1
PRC: Confirming active lease (INIT-REBOOT).
XMT: Forming Rebind, 0 ms elapsed.
XMT:  X-- IA_PD 35:07:ad:18
XMT:  | X-- Requested renew  +3600
XMT:  | X-- Requested rebind +5400
XMT:  | | X-- IAPREFIX 2001:bc8:344f:200::/56
XMT:  | | | X-- Preferred lifetime +7200
XMT:  | | | X-- Max lifetime +7500
XMT:  V IA_PD appended.
XMT: Rebind on eno1, interval 1030ms.
RCV: Reply message on eno1 from fe80::fe5b:39ff:fe72:9fff.
RCV:  X-- Preference 255.
RCV:  X-- IA_PD 35:07:ad:18
RCV:  | X-- starts 1485444775
RCV:  | X-- t1 - renew  +43200
RCV:  | X-- t2 - rebind +172800
RCV:  | X-- [Options]
RCV:  | | X-- IAPREFIX 2001:bc8:344f:200::/56
RCV:  | | | X-- Preferred lifetime 7200.
RCV:  | | | X-- Max lifetime 43200.
RCV:  X-- Server ID: 00:01:00:01:1b:ac:bc:2d:10:60:4b:9b:0a:f4
PRC: Bound to lease 00:01:00:01:1b:ac:bc:2d:10:60:4b:9b:0a:f4.

and

# ifconfig eno1
eno1      Link encap:Ethernet  HWaddr 54:9f:35:07:ad:18
           inet addr:62.210.247.117  Bcast:62.210.247.255 
Mask:255.255.255.0
           inet6 addr: fe80::569f:35ff:fe07:ad18/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:25519061 errors:0 dropped:0 overruns:0 frame:0
           TX packets:52829191 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:1920059401 (1.9 GB)  TX bytes:79910066020 (79.9 GB)
           Interrupt:16

For my ISP, all is good but I have no IPV6 connection.
thanks for your tips,

-- 
Jean-Max Reymond
CKR Solutions Open Source https://www.ckr-solutions.com