IPv6 DHCP Issues

[pingloss]

I've come across an odd issue after just moving ISP's where my IPv6 traffic is bouncing up and down every 5 minutes. I've worked out it's linked to the IPv6 DHCP renewal that's taking place every 5 minutes but I don't know if it's setup error on my or their side? It wasn't occurring prior to the move this morning so logic says it's an issue on their side but I'd like to sanity check myself.

I see the following log entries when the IPv6 traffic works

2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : wireguard_sync())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : webgui_configure_do(,[wan,opt4]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : vxlan_configure_do())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : unbound_configure_do(,[wan,opt4]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : openssh_configure_do(,[wan,opt4]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : opendns_configure_do())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : ntpd_configure_do())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: miniupnpd: Starting service on interface: opt7, lan
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : miniupnpd_configure_do())
2026-02-05T13:37:50   Warning   igmpproxy    select() failure; Errno(4): Interrupted system call
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : igmpproxy_configure_do())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : dhcrelay_configure_if(,[wan,opt4],inet6))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (,[wan,opt4],inet6)
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : wireguard_configure_do())
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : openvpn_configure_do(,[wan,opt4]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : ipsec_configure_do(,[wan,opt4]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure vpn (,[wan,opt4],inet6)
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure monitor (execute task : dpinger_configure_do(,[WAN_DHCP6]))
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure monitor (,[WAN_DHCP6])
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: ROUTING: keeping inet6 default route to fe80::e65d:37ff:fe91:e88b%igc0
2026-02-05T13:37:50   Notice   opnsense    /usr/local/etc/rc.newwanipv6: ROUTING: configuring inet6 default gateway on wan
2026-02-05T13:37:49   Notice   opnsense    /usr/local/etc/rc.newwanipv6: ROUTING: entering configure using wan, opt4
2026-02-05T13:37:49   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure dhcp (execute task : radvd_configure_dhcp(,inet6))
2026-02-05T13:37:49   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure dhcp (execute task : dhcpd_dhcp_configure(,inet6))
2026-02-05T13:37:49   Notice   opnsense    /usr/local/etc/rc.newwanipv6: plugins_configure dhcp (,inet6)
2026-02-05T13:37:49   Notice   opnsense    /usr/local/etc/rc.newwanipv6: IP renewal starting (reason: request, address: fe80::baff:b3ff:fe06:6f1a%igc0, interface: wan, device: igc0)
2026-02-05T13:37:45   Notice   dhcp6c    got an expected reply, sleeping.
2026-02-05T13:37:45   Notice   dhcp6c    script "/var/etc/dhcp6c_wan_script.sh" terminated
2026-02-05T13:37:45   Notice   dhcp6c    dhcp6c_script: REQUEST on igc0 prefix now xxxx:xxxx:2938::/48
2026-02-05T13:37:45   Notice   dhcp6c    dhcp6c_script: REQUEST on igc0 connected to server
2026-02-05T13:37:45   Notice   dhcp6c    dhcp6c_script: REQUEST on igc0 executing
2026-02-05T13:37:45   Notice   dhcp6c    executes /var/etc/dhcp6c_wan_script.sh
2026-02-05T13:37:45   Notice   dhcp6c    removing server (ID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00)
2026-02-05T13:37:45   Notice   dhcp6c    removing an event on igc0, state=REQUEST
2026-02-05T13:37:45   Notice   dhcp6c    add an address xxxx:xxxx:xxxx:x:xxxx:xxxx:xxxx:1642/48 on vlan0.20
2026-02-05T13:37:45   Notice   dhcp6c    create a prefix xxxx:xxxx:2938::/48 pltime=600, vltime=600
2026-02-05T13:37:45   Notice   dhcp6c    make an IA: PD-0
2026-02-05T13:37:45   Notice   dhcp6c    Domain name server[1] 2a02:8010:6:0:212:23:6:100
2026-02-05T13:37:45   Notice   dhcp6c    Domain name server[0] 2a02:8010:6:0:212:23:3:100
2026-02-05T13:37:45   Notice   dhcp6c    Received REPLY for REQUEST
2026-02-05T13:37:45   Notice   dhcp6c    get DHCP option DNS, len 32
2026-02-05T13:37:45   Notice   dhcp6c      IA_PD prefix: xxxx:xxxx:xxxx::/48 pltime=600 vltime=600
2026-02-05T13:37:45   Notice   dhcp6c    get DHCP option IA_PD prefix, len 25
2026-02-05T13:37:45   Notice   dhcp6c      IA_PD: ID=0, T1=300, T2=480
2026-02-05T13:37:45   Notice   dhcp6c    get DHCP option IA_PD, len 41
2026-02-05T13:37:45   Notice   dhcp6c      DUID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00
2026-02-05T13:37:45   Notice   dhcp6c    get DHCP option server ID, len 26
2026-02-05T13:37:45   Notice   dhcp6c      DUID: 00:01:00:01:2f:04:80:83:60:be:b4:1e:16:40
2026-02-05T13:37:45   Notice   dhcp6c    get DHCP option client ID, len 14
2026-02-05T13:37:45   Notice   dhcp6c    receive reply from fe80::e65d:37ff:fe91:e88b%igc0 on igc0
2026-02-05T13:37:45   Notice   dhcp6c    reset a timer on igc0, state=REQUEST, timeo=0, retrans=1072
2026-02-05T13:37:45   Notice   dhcp6c    send request to ff02::1:2%igc0
2026-02-05T13:37:45   Notice   dhcp6c    set IA_PD
2026-02-05T13:37:45   Notice   dhcp6c    set IA_PD prefix
2026-02-05T13:37:45   Notice   dhcp6c    set option request (len 4)
2026-02-05T13:37:45   Notice   dhcp6c    set elapsed time (len 2)
2026-02-05T13:37:45   Notice   dhcp6c    set server ID (len 26)
2026-02-05T13:37:45   Notice   dhcp6c    set client ID (len 14)
2026-02-05T13:37:45   Notice   dhcp6c    a new XID (21be65) is generated
2026-02-05T13:37:45   Notice   dhcp6c    Sending Request on igc0
2026-02-05T13:37:45   Notice   dhcp6c    picked a server (ID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00)
2026-02-05T13:37:44   Notice   dhcp6c    reset timer for igc0 to 0.833093
2026-02-05T13:37:44   Notice   dhcp6c    server ID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00, pref=-1
2026-02-05T13:37:44   Notice   dhcp6c    get DHCP option DNS, len 32
2026-02-05T13:37:44   Notice   dhcp6c      IA_PD prefix: xxxx:xxxx:xxxx::/48 pltime=600 vltime=600
2026-02-05T13:37:44   Notice   dhcp6c    get DHCP option IA_PD prefix, len 25
2026-02-05T13:37:44   Notice   dhcp6c      IA_PD: ID=0, T1=300, T2=480
2026-02-05T13:37:44   Notice   dhcp6c    get DHCP option IA_PD, len 41
2026-02-05T13:37:44   Notice   dhcp6c      DUID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00
2026-02-05T13:37:44   Notice   dhcp6c    get DHCP option server ID, len 26
2026-02-05T13:37:44   Notice   dhcp6c      DUID: 00:01:00:01:2f:04:80:83:60:be:b4:1e:16:40
2026-02-05T13:37:44   Notice   dhcp6c    get DHCP option client ID, len 14
2026-02-05T13:37:44   Notice   dhcp6c    receive advertise from fe80::e65d:37ff:fe91:e88b%igc0 on igc0
2026-02-05T13:37:44   Notice   dhcp6c    reset a timer on igc0, state=SOLICIT, timeo=0, retrans=1021
2026-02-05T13:37:44   Notice   dhcp6c    send solicit to ff02::1:2%igc0
2026-02-05T13:37:44   Notice   dhcp6c    set IA_PD
2026-02-05T13:37:44   Notice   dhcp6c    set IA_PD prefix
2026-02-05T13:37:44   Notice   dhcp6c    set option request (len 4)
2026-02-05T13:37:44   Notice   dhcp6c    set elapsed time (len 2)
2026-02-05T13:37:44   Notice   dhcp6c    set client ID (len 14)
2026-02-05T13:37:44   Notice   dhcp6c    a new XID (231bfa) is generated
2026-02-05T13:37:44   Notice   dhcp6c    Sending Solicit on igc0
2026-02-05T13:37:43   Notice   dhcp6c    got an expected reply, sleeping.
2026-02-05T13:37:43   Notice   dhcp6c    script "/var/etc/dhcp6c_wan_script.sh" terminated
2026-02-05T13:37:43   Notice   dhcp6c    dhcp6c_script: RENEW on igc0 executing
2026-02-05T13:37:43   Notice   dhcp6c    executes /var/etc/dhcp6c_wan_script.sh
2026-02-05T13:37:43   Notice   dhcp6c    removing an event on igc0, state=RENEW
2026-02-05T13:37:43   Notice   dhcp6c    reset a timer on igc0, state=INIT, timeo=0, retrans=819
2026-02-05T13:37:43   Notice   dhcp6c    remove an IA: PD-0
2026-02-05T13:37:43   Notice   dhcp6c    IA PD-0 is invalidated
2026-02-05T13:37:43   Notice   dhcp6c    remove an address xxxx:xxxx:xxxx:x:xxxx:xxxx:xxxx:1642/48 on vlan0.20
2026-02-05T13:37:43   Notice   dhcp6c    remove a site prefix xxxx:xxxx:xxxx::/48
2026-02-05T13:37:43   Notice   dhcp6c    update a prefix xxxx:xxxx:xxxx::/48 pltime=0, vltime=0
2026-02-05T13:37:43   Notice   dhcp6c    update an IA: PD-0
2026-02-05T13:37:43   Notice   dhcp6c    Received REPLY for RENEW
2026-02-05T13:37:43   Notice   dhcp6c      status code: no binding
2026-02-05T13:37:43   Notice   dhcp6c    get DHCP option status code, len 29
2026-02-05T13:37:43   Notice   dhcp6c      IA_PD prefix: xxxx:xxxx:xxxx::/48 pltime=0 vltime=0
2026-02-05T13:37:43   Notice   dhcp6c    get DHCP option IA_PD prefix, len 58
2026-02-05T13:37:43   Notice   dhcp6c      IA_PD: ID=0, T1=0, T2=0
2026-02-05T13:37:43   Notice   dhcp6c    get DHCP option IA_PD, len 74
2026-02-05T13:37:43   Notice   dhcp6c      DUID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00
2026-02-05T13:37:43   Notice   dhcp6c    get DHCP option server ID, len 26
2026-02-05T13:37:43   Notice   dhcp6c      DUID: 00:01:00:01:2f:04:80:83:60:be:b4:1e:16:40
2026-02-05T13:37:43   Notice   dhcp6c    get DHCP option client ID, len 14
2026-02-05T13:37:43   Notice   dhcp6c    receive reply from fe80::e65d:37ff:fe91:e88b%igc0 on igc0
2026-02-05T13:37:43   Notice   dhcp6c    send renew to ff02::1:2%igc0
2026-02-05T13:37:43   Notice   dhcp6c    set IA_PD
2026-02-05T13:37:43   Notice   dhcp6c    set IA_PD prefix
2026-02-05T13:37:43   Notice   dhcp6c    set option request (len 4)
2026-02-05T13:37:43   Notice   dhcp6c    set elapsed time (len 2)
2026-02-05T13:37:43   Notice   dhcp6c    set server ID (len 26)
2026-02-05T13:37:43   Notice   dhcp6c    set client ID (len 14)
2026-02-05T13:37:43   Notice   dhcp6c    a new XID (f06898) is generated
2026-02-05T13:37:43   Notice   dhcp6c    Sending Renew on igc0
2026-02-05T13:37:43   Notice   dhcp6c    reset a timer on igc0, state=RENEW, timeo=0, retrans=10503
2026-02-05T13:37:43   Notice   dhcp6c    IA timeout for PD-0, state=ACTIVE
2026-02-05T13:37:30   Notice   dhclient    dhclient-script: Creating resolv.conf
2026-02-05T13:37:30   Notice   dhclient    dhclient-script: Reason RENEW on igc0 executing

After 5 mins the IPv6 DHCP renew occurs and it all stops working

2026-02-05T13:42:45   Notice   dhcp6c    got an expected reply, sleeping.
2026-02-05T13:42:45   Notice   dhcp6c    script "/var/etc/dhcp6c_wan_script.sh" terminated
2026-02-05T13:42:45   Notice   dhcp6c    dhcp6c_script: RENEW on igc0 executing
2026-02-05T13:42:45   Notice   dhcp6c    executes /var/etc/dhcp6c_wan_script.sh
2026-02-05T13:42:45   Notice   dhcp6c    removing an event on igc0, state=RENEW
2026-02-05T13:42:45   Notice   dhcp6c    add an address xxxx:xxxx:xxxx:x:xxxx:xxxx:xxxx:1642/48 on vlan0.20
2026-02-05T13:42:45   Notice   dhcp6c    update a prefix xxxx:xxxx:xxxx::/48 pltime=600, vltime=600
2026-02-05T13:42:45   Notice   dhcp6c    update an IA: PD-0
2026-02-05T13:42:45   Notice   dhcp6c    Domain name server[1] 2a02:8010:6:0:212:23:6:100
2026-02-05T13:42:45   Notice   dhcp6c    Domain name server[0] 2a02:8010:6:0:212:23:3:100
2026-02-05T13:42:45   Notice   dhcp6c    Received REPLY for RENEW
2026-02-05T13:42:45   Notice   dhcp6c    get DHCP option DNS, len 32
2026-02-05T13:42:45   Notice   dhcp6c      IA_PD prefix: xxxx:xxxx:xxxx::/48 pltime=600 vltime=600
2026-02-05T13:42:45   Notice   dhcp6c    get DHCP option IA_PD prefix, len 25
2026-02-05T13:42:45   Notice   dhcp6c      IA_PD: ID=0, T1=300, T2=480
2026-02-05T13:42:45   Notice   dhcp6c    get DHCP option IA_PD, len 41
2026-02-05T13:42:45   Notice   dhcp6c      DUID: 00:02:00:00:05:83:65:34:3a:35:64:3a:33:37:3a:39:31:3a:66:30:3a:36:34:00:00:00
2026-02-05T13:42:45   Notice   dhcp6c    get DHCP option server ID, len 26
2026-02-05T13:42:45   Notice   dhcp6c      DUID: 00:01:00:01:2f:04:80:83:60:be:b4:1e:16:40
2026-02-05T13:42:45   Notice   dhcp6c    get DHCP option client ID, len 14
2026-02-05T13:42:45   Notice   dhcp6c    receive reply from fe80::e65d:37ff:fe91:e88b%igc0 on igc0
2026-02-05T13:42:45   Notice   dhcp6c    send renew to ff02::1:2%igc0
2026-02-05T13:42:45   Notice   dhcp6c    set IA_PD
2026-02-05T13:42:45   Notice   dhcp6c    set IA_PD prefix
2026-02-05T13:42:45   Notice   dhcp6c    set option request (len 4)
2026-02-05T13:42:45   Notice   dhcp6c    set elapsed time (len 2)
2026-02-05T13:42:45   Notice   dhcp6c    set server ID (len 26)
2026-02-05T13:42:45   Notice   dhcp6c    set client ID (len 14)
2026-02-05T13:42:45   Notice   dhcp6c    a new XID (cae521) is generated
2026-02-05T13:42:45   Notice   dhcp6c    Sending Renew on igc0
2026-02-05T13:42:45   Notice   dhcp6c    reset a timer on igc0, state=RENEW, timeo=0, retrans=9493
2026-02-05T13:42:45   Notice   dhcp6c    IA timeout for PD-0, state=ACTIVE
2026-02-05T13:42:30   Notice   dhclient    dhclient-script: Creating resolv.conf
2026-02-05T13:42:30   Notice   dhclient    dhclient-script: Reason RENEW on igc0 executing

The process goes around in another 5 mins and traffic starts to flow again. I've logged the issue with my new ISP but I just wanted to know if there's anything on my side I'm not understanding?

[franco]

> IA_PD prefix: xxxx:xxxx:xxxx::/48 pltime=600 vltime=600

Your ISP proposes a lifetime of 10 minutes. The client will honour it and try to renew the lease after 5 minutes.

Ask your ISP to set more conservative lifetime (pltime/vltime) defaults.

In theory we could add lifetime request values in the GUI but

1) nobody needed it so far
2) I'm not even sure it works reliably since the server has to decide


Cheers,
Franco

[pingloss]

Thanks Franco, you've confirmed my thoughts and it's what I've requested back to my new ISP.

[agh1701]

how do find the pltime and vltime values?  Thanks.

[franco]

They are in the debug log of dhcp6c (Interfaces: Settings: IPv6 debug) but need a restart or kill of dhcp6c process to be set in the daemon.


Cheers,
Franco

[agh1701]

Thanks, I have that set.  is there any place to view this other than the logs?