Package: isc-dhcp-server Version: 4.3.5-3 Followup-For: Bug #882250 I can confirm this bug after upgrading from Debian 8 Jessie to Debian 9 Stretch.
I am running isc-dhcp-server in both v4 and v6 mode on a number of interfaces, one LAN and several WLAN interfaces. Before upgrade, clients got v6 addresses on all interfaces. After upgrade, only WLAN clients get v6 addresses from isc-dhcp-server. Whenever LAN clients connect, I see solicit messages in the isc-dhcp-server logs and in tcpdump output, but there's never sent an answer. Radvd and ipv4 works fine on all interfaces. The only difference between LAN and WLAN interface is that the LAN interface has some additional addresses used as listening addresses by a local squid proxy and that it has a global dynamic address assigned by the ISP. Some configuration and debugging information: root@prokyon:/etc/dhcp# ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.0.251 netmask 255.255.255.0 broadcast 192.168.0.255 inet6 fd10:2842:f0d1:101:20d:b9ff:fe0d:84b0 prefixlen 128 scopeid 0x0<global> inet6 2001:472:7d:977::53 prefixlen 128 scopeid 0x0<global> inet6 2001:a61:4619:8f01::1 prefixlen 64 scopeid 0x0<global> inet6 fd10:3d52:f521::13 prefixlen 128 scopeid 0x0<global> inet6 2001:472:7d:977::13 prefixlen 128 scopeid 0x0<global> inet6 fd10:5d12:c721::13 prefixlen 128 scopeid 0x0<global> inet6 fd10:2842:f0d1::13 prefixlen 128 scopeid 0x0<global> inet6 fd10:7d41:b631::13 prefixlen 128 scopeid 0x0<global> inet6 2001:472:52b5:101:20d:b9ff:fe0d:84b0 prefixlen 128 scopeid 0x0<global> inet6 fe80::20d:b9ff:fe0d:84b0 prefixlen 64 scopeid 0x20<link> ether 00:0d:b9:0d:84:b0 txqueuelen 1000 (Ethernet) RX packets 9329004 bytes 6196176943 (5.7 GiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 7248452 bytes 4465680935 (4.1 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 root@prokyon:/etc/dhcp# ifconfig wlan0 wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.123 netmask 255.255.255.128 broadcast 192.168.1.127 inet6 2001:472:52b5:202:a5:4ff:fe3d:9610 prefixlen 128 scopeid 0x0<global> inet6 fd10:2842:f0d1:202:a5:4ff:fe3d:9610 prefixlen 128 scopeid 0x0<global> inet6 fe80::a5:4ff:fe3d:9610 prefixlen 64 scopeid 0x20<link> ether 02:a5:04:3d:96:10 txqueuelen 1000 (Ethernet) RX packets 645631 bytes 147489457 (140.6 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 813939 bytes 494687778 (471.7 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 dhcpd6.conf: subnet6 fd10:2842:f0d1:101::/64 { # lan # Range for clients range6 fd10:2842:f0d1:101:af31:9c41:dd6b:7a4 fd10:2842:f0d1:101:af31:9c41:dd6b:7c4; # Range for clients requesting a temporary address range6 fd10:2842:f0d1:101::/64 temporary; # Additional options option dhcp6.name-servers fd10:2842:f0d1:101:20d:b9ff:fe0d:84b0; option dhcp6.sntp-servers fd10:2842:f0d1:101:20d:b9ff:fe0d:84b0; option dhcp6.domain-search "its-me.de"; # Prefix range for delegation to sub-routers #prefix6 2001:472:7c:100:: 2001:db8:0:f00:: /56; ddns-domainname "its-me.de."; ddns-rev-domainname "ip6.arpa."; } subnet6 fd10:2842:f0d1:202::/64 { # wlan # Range for clients range6 fd10:2842:f0d1:202:5d32:abf3:7de2:5d3 fd10:2842:f0d1:202:5d32:abf3:7de2:5f3; # Range for clients requesting a temporary address range6 fd10:2842:f0d1:202::/64 temporary; # Additional options option dhcp6.name-servers fd10:2842:f0d1:101:20d:b9ff:fe0d:84b0; option dhcp6.sntp-servers fd10:2842:f0d1:101:20d:b9ff:fe0d:84b0; option dhcp6.domain-search "its-me.de"; # Prefix range for delegation to sub-routers #prefix6 2001:472:7c:100:: 2001:db8:0:f00:: /56; ddns-domainname "its-me.de."; ddns-rev-domainname "ip6.arpa."; } dhcpd.log: (LAN client, broken) Dec 28 01:41:51 prokyon dhcpd[27274]: Solicit message from fe80::230:5ff:fe96:90dd port 546, transaction ID 0x925C6800 Dec 28 01:41:53 prokyon dhcpd[27274]: Solicit message from fe80::230:5ff:fe96:90dd port 546, transaction ID 0x925C6800 Dec 28 01:41:55 prokyon dhcpd[27274]: Solicit message from fe80::230:5ff:fe96:90dd port 546, transaction ID 0x925C6800 Dec 28 01:41:59 prokyon dhcpd[27274]: Solicit message from fe80::230:5ff:fe96:90dd port 546, transaction ID 0x925C6800 Dec 28 01:42:07 prokyon dhcpd[27274]: Solicit message from fe80::230:5ff:fe96:90dd port 546, transaction ID 0x925C6800 tcpdump: (LAN client, broken) 01:42:44.628547 IP6 fe80::230:5ff:fe96:90dd.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit 01:42:45.699812 IP6 fe80::230:5ff:fe96:90dd.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit 01:42:47.902235 IP6 fe80::230:5ff:fe96:90dd.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit 01:42:52.096659 IP6 fe80::230:5ff:fe96:90dd.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit 01:43:00.885703 IP6 fe80::230:5ff:fe96:90dd.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit dhcpd.log: (WLAN client, okay) Dec 28 01:42:58 prokyon dhcpd[27274]: Renew message from fe80::21f:e1ff:fe1d:61 port 546, transaction ID 0xEF0D5700 Dec 28 01:42:58 prokyon dhcpd[27274]: Reply NA: address fd10:2842:f0d1:202:5d32:abf3:7de2:5f1 to client with duid 00:04:9d:83:51:09:62:93:3d:bb:05:9f:95:24:50:3f:5c:f2 iaid = -518193055 valid for 1200 seconds tcpdump: (WLAN client, okay) 01:47:15.872782 IP6 fe80::21f:e1ff:fe1d:61.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 confirm 01:47:15.872902 IP6 fe80::21f:e1ff:fe1d:61.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 confirm 01:47:15.899030 IP6 fe80::a5:4ff:fe3d:9610.dhcpv6-server > fe80::21f:e1ff:fe1d:61.dhcpv6-client: dhcp6 reply -- System Information: Debian Release: 9.3 APT prefers stable-updates APT policy: (500, 'stable-updates'), (500, 'stable') Architecture: amd64 (x86_64) Kernel: Linux 4.9.0-4-amd64 (SMP w/2 CPU cores) Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=de_DE.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) Versions of packages isc-dhcp-server depends on: ii debconf [debconf-2.0] 1.5.61 ii debianutils 4.8.1.1 ii libc6 2.24-11+deb9u1 ii libdns-export162 1:9.10.3.dfsg.P4-12.3+deb9u3 ii libirs-export141 1:9.10.3.dfsg.P4-12.3+deb9u3 ii libisc-export160 1:9.10.3.dfsg.P4-12.3+deb9u3 ii lsb-base 9.20161125 Versions of packages isc-dhcp-server recommends: ii isc-dhcp-common 4.3.5-3 ii policycoreutils 2.6-3 Versions of packages isc-dhcp-server suggests: pn isc-dhcp-server-ldap <none> ii policykit-1 0.105-18 -- Configuration Files: /etc/dhcp/dhcpd.conf changed [not included] /etc/dhcp/dhcpd6.conf changed [not included] -- debconf information excluded