ubuntu 16.04 chrony 同步时间失败？ 主机上网正常，查询了 google stackoverflow stackexchange 也没有解决办法,请问大家有没有遇到过，如何解决的？ 谢谢！

系统系统如下：

root@ansible_fwssr:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.04.6 LTS Release: 16.04 Codename: xenial

具体信息如下 root@ansible_fwssr:~# chronyc sources -v 210 Number of sources = 8

.-- Source mode '^' = server, '=' = peer, '#' = local clock. / .- Source state '*' = current synced, '+' = combined , '-' = not combined, | / '?' = unreachable, 'x' = time may be in error, '~' = time too variable. || .- xxxx [ yyyy ] +/- zzzz || Reachability register (octal) -. | xxxx = adjusted offset, || Log2(Polling interval) --. | | yyyy = measured offset, || \ | | zzzz = estimated error. || | |
MS Name/IP address Stratum Poll Reach LastRx Last sample

^? ntp6.flashdance.cx 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? b9d1-55de.led01.ru.misaka 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? h199-182-204-197.ip4.unme 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? 124-108-20-1.static.betai 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? stratum2-1.ntp.sea03.us.m 0 7 0 10y +0ns[ +0ns] +/- 0ns ^? ntp5.flashdance.cx 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? ntp1.ams1.nl.leaseweb.net 0 6 0 10y +0ns[ +0ns] +/- 0ns ^? lb02-dc02.no-mans-land.co 0 6 0 10y +0ns[ +0ns] +/- 0ns