Can't update time on Dom0 with ntp running on DomU(PFsense)

[logik]

Hi everybody.

So the machine run on Xenserver 6.5SP1 with a domU running pfsense 2.2.4.
And I can't update time on the Xenserver with pfsense domU.

Xenserver report an error stratum 16 when I want to update from PFsense NTP Server. (tested with NTPd and ntpdate.)(the daemon report to be a stratum 3)

The DomU (pfsense) is the NTP server.
The DomU (debian) is a ntp client.
The DomU (Openmediavault) is a ntp client and ntp server.
The Dom0 (Xenserver) is a ntp client
Non-Virtualized computer running Debian as ntp client or server.

To resume:
Dom0 can update time from pool.ntp.org/Openmediavault DomU ntp Server/Non-Virtualized Debian NTP server.
All DomU can update time from PFsense (domU)
Non-virtualized Computer can update time from PFsense(DomU)

BUT Dom0 CAN'T update time from PFsense(DomU)
So I don't know if it's a XenServer or PFsense problem…
I hope to have been clear.

Regards.