NTPD IPv6 connection problem

[Richard Ames]

My NTP server on a VPS dies occasionally (twice now) ... which results in a service interruption. See https://www.ntppool.org/scores/203.57.51.100

Looking in the syslog shows:

Aug 21 03:29:56 combine-window dhclient[507]: DHCPREQUEST for 203.57.51.100 on eth0 to 103.16.128.248 port 67 (xid=0x4311e9a7)
Aug 21 03:29:56 combine-window dhclient[507]: DHCPACK of 203.57.51.100 from 103.16.128.248 (xid=0xa7e91143)
Aug 21 03:29:56 combine-window dhclient[507]: bound to 203.57.51.100 -- renewal in 274 seconds.
Aug 21 03:30:01 combine-window CRON[23839]: (nobody) CMD (/usr/local/bin/mpanel-memory-graph)
Aug 21 03:31:20 combine-window ntpd[814]: bind(25) AF_INET6 2404:9400:1:0:216:3eff:fef2:1a8a#123 flags 0x11 failed: Cannot assign requested address
Aug 21 03:31:20 combine-window ntpd[814]: unable to create socket on eth0 (6) for 2404:9400:1:0:216:3eff:fef2:1a8a#123
Aug 21 03:31:20 combine-window ntpd[814]: failed to init interface for address 2404:9400:1:0:216:3eff:fef2:1a8a
Aug 21 03:31:22 combine-window ntpd[814]: Listen normally on 7 eth0 [2404:9400:1:0:216:3eff:fef2:1a8a]:123
Aug 21 03:31:22 combine-window ntpd[814]: new interface(s) found: waking up resolver
Aug 21 03:31:29 combine-window ntpd[814]: Deleting interface #7 eth0, 2404:9400:1:0:216:3eff:fef2:1a8a#123, interface stats: received=0, sent=0, dropped=0, active_time=7 secs

I am currently prevent the problem by making NTP ipv4 only.

Can anyone suggest what causes this problem???

Thank you, Richard.

[Richard Ames]

The virtual server did not have ipv6 turned on … so there was only a link local ipv6 address. My error for not knowing this.

It is now on and I can ping6 across the country. Will enable ipv6 on NTP and see if the problem recurs…