Les message XMT sollicit provenaient de mon dhclient ipv6.
Je viens de restarter mon ONT puis restart dhclient.
Plus de messages XMT: Sollicit ... 
Mais maintenant, j'ai des messages XMT : Request
Pourtant, j'ai affecté manuellement une ipv6 de mon prefix sur ma carte orange2 (comme avant) :
# ip addr show dev orange2
334: orange2@wan2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc prio state UP group default qlen 1000
    link/ether 44:d4:54:0a:44:20 brd ff:ff:ff:ff:ff:ff
    inet xxxx/24 brd xxx.255 scope global orange2
       valid_lft forever preferred_lft forever
    inet6 2a01:cb15:3e4:7000::2:254/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::46d4:54ff:fe0a:4420/64 scope link
       valid_lft forever preferred_lft forever
En VDSL tout marchait bien ipv4 et ipv6. En fibre, il y a qque chose qui a changé et je ne sais pas quoi ...
PRC: Soliciting for leases (INIT).
XMT: Forming Solicit, 0 ms elapsed.
XMT:  X-- IA_PD 54:0a:44:20
XMT:  | X-- Request renew in  +3600
XMT:  | X-- Request rebind in +5400
XMT: Solicit on orange2, interval 1090ms.
RCV: Advertise message on orange2 from fe80::ba0:bab.
RCV:  X-- Preference 255.
RCV:  X-- IA_PD 54:0a:44:20
RCV:  | X-- starts 1658156796
RCV:  | X-- t1 - renew  +91257
RCV:  | X-- t2 - rebind +207360
RCV:  | X-- [Options]
RCV:  | | X-- IAPREFIX 2a01:cb15:3e4:7000::/56
RCV:  | | | X-- Preferred lifetime 259200.
RCV:  | | | X-- Max lifetime 259200.
RCV:  X-- Server ID:
RCV:  Advertisement immediately selected.
PRC: Selecting best advertised lease.
PRC: Considering best lease.
PRC:  X-- Initial candidate  (s: 10104, p: 255).
XMT: Forming Request, 0 ms elapsed.
XMT:  X-- IA_PD 54:0a:44:20
XMT:  | X-- Requested renew  +3600
XMT:  | X-- Requested rebind +5400
XMT:  | | X-- IAPREFIX 2a01:cb15:3e4:7000::/56
XMT:  | | | X-- Preferred lifetime +7200
XMT:  | | | X-- Max lifetime +7500
XMT:  V IA_PD appended.
XMT: Request on orange2, interval 930ms.
XMT: Forming Request, 930 ms elapsed.
XMT:  X-- IA_PD 54:0a:44:20
XMT:  | X-- Requested renew  +3600
XMT:  | X-- Requested rebind +5400
XMT:  | | X-- IAPREFIX 2a01:cb15:3e4:7000::/56
XMT:  | | | X-- Preferred lifetime +7200
XMT:  | | | X-- Max lifetime +7500
XMT:  V IA_PD appended.
XMT: Request on orange2, interval 1940ms.
une idée ?
merci