I followed the advice on DHCPv6 option6 for downstreams and added
option:ntp-server,192.168.1.1
option6:ntp-server,[fd22::1]
but it is not working, running tcp dump shows
tcpdump: listening on enp0s25, link-type EN10MB (Ethernet), snapshot length 262144 bytes
23:42:42.703213 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 120) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x562a -> 0xd10f!] dhcp6 confirm (xid=749692 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 0) (IA_NA IAID:1942487358 T1:0 T2:0 (IA_ADDR xxx:xxx:xxx:xxx:xxxx pltime:0 vltime:0) (IA_ADDR fd88::eac pltime:0 vltime:0)))
23:42:42.704015 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 78) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 reply (xid=749692 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (status-code NotOnLink))
23:42:43.324963 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 64) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x55f2 -> 0x2a85!] dhcp6 solicit (xid=d24f70 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 0) (IA_NA IAID:1942487358 T1:3600 T2:5400))
23:42:43.325767 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 94) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 advertise (xid=d24f70 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (IA_NA IAID:1942487358 T1:0 T2:0 (status-code NoAddrsAvail)))
23:42:44.406228 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 64) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x55f2 -> 0x2a19!] dhcp6 solicit (xid=d24f70 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 108) (IA_NA IAID:1942487358 T1:3600 T2:5400))
23:42:44.406928 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 94) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 advertise (xid=d24f70 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (IA_NA IAID:1942487358 T1:0 T2:0 (status-code NoAddrsAvail)))
23:42:46.597011 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 64) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x55f2 -> 0x293e!] dhcp6 solicit (xid=d24f70 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 327) (IA_NA IAID:1942487358 T1:3600 T2:5400))
23:42:46.597749 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 94) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 advertise (xid=d24f70 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (IA_NA IAID:1942487358 T1:0 T2:0 (status-code NoAddrsAvail)))
23:42:50.880997 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 64) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x55f2 -> 0x2792!] dhcp6 solicit (xid=d24f70 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 755) (IA_NA IAID:1942487358 T1:3600 T2:5400))
23:42:50.881753 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 94) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 advertise (xid=d24f70 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (IA_NA IAID:1942487358 T1:0 T2:0 (status-code NoAddrsAvail)))
23:42:59.297021 IP6 (flowlabel 0x5116a, hlim 1, next-header UDP (17) payload length: 64) fe80::b433:a2fc:f3e5:d04.546 > ff02::1:2.547: [bad udp cksum 0x55f2 -> 0x2448!] dhcp6 solicit (xid=d24f70 (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (option-request DNS-server DNS-search-list Client-FQDN SNTP-servers) (elapsed-time 1597) (IA_NA IAID:1942487358 T1:3600 T2:5400))
23:42:59.297745 IP6 (flowlabel 0x73461, hlim 64, next-header UDP (17) payload length: 94) fe80::b675:eff:fefd:69f6.547 > fe80::b433:a2fc:f3e5:d04.546: [udp sum ok] dhcp6 advertise (xid=d24f70 (server-ID hwaddr type 1 b4750efd69f6) (client-ID hwaddr/time type 1 time 734844943 180373c8013e) (opt_82) (DNS-server fd22::1) (IA_NA IAID:1942487358 T1:0 T2:0 (status-code NoAddrsAvail)))
Can anyone verify that ntp server for DHCPv6 works? I removed dnsmasq and installed dnsmasq-full and rebooted the router.