pppoe reconnect can't release old ipv6 address

I installed ubuntu 22.04 and enable ipv6 in pppoe network,but I found pppoeconf doesn't release old ipv6 address whenISP auto disconnect and re-connect with the network.

Does anyone know how to fixed this problem? Thanks

1. uname -a

Linux xxxxxxxx 5.15.0-83-generic #92-Ubuntu SMP Mon Aug 14 09:30:42 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

2. dpkg -l | grep pppoe

ii pppoeconf 1.21+nmu2ubuntu1 all configures PPPoE/ADSL connections

3. /etc/netplan# cat 00-installer-config.yaml

# This is the network config written by 'subiquity'network:  version: 2  renderer: networkd  ethernets:    enp2s0:      addresses:      - 192.168.1.xxx/24      nameservers:        addresses:        - 8.8.8.8        - xxx.xx.xx.xx        search:        - xxxx.xxxx.xxxx      routes:        - to: default          via: 192.168.1.1

4. /etc/network$ cat interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)# Include files from /etc/network/interfaces.d:source /etc/network/interfaces.d/*auto dsl-provideriface dsl-provider inet ppppre-up /bin/ip link set enp2s0 up # line maintained by pppoeconfprovider dsl-providerauto enp2s0#iface enp2s0 inet dhcpiface enp2s0 inet manual

5. /etc/ppp/peers$ cat dsl-provider

# Minimalistic default options file for DSL/PPPoE connectionsnoipdefaultdefaultroutereplacedefaultroutehide-passwordlcp-echo-interval 30lcp-echo-failure 4noauthpersist#mtu 1492#persistmaxfail 0holdoff 20plugin rp-pppoe.sonic-enp2s0user "xxxx@xxxxx"usepeerdns

6. vi /etc/ppp/options

# enable ipv6 in ppp+ipv6 ipv6cp-use-ipaddr

7. vi /etc/sysctl.conf

net.ipv6.conf.all.forwarding=1net.ipv6.conf.ppp0.accept_ra=2

8. ifconfig

enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500        inet 192.168.1.xxx netmask 255.255.255.0 broadcast 192.168.1.255        inet6 fe80::feaa:14ff:fe41:xxxx prefixlen 64 scopeid 0x20<link>        ether fc:aa:14:xx:xx:xx txqueuelen 1000 (Ethernet)        RX packets 1104036 bytes 270179711 (270.1 MB)        RX errors 0 dropped 0 overruns 0 frame 0        TX packets 975912 bytes 1012802190 (1.0 GB)        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536        inet 127.0.0.1 netmask 255.0.0.0        inet6 ::1 prefixlen 128 scopeid 0x10<host>        loop txqueuelen 1000 (Local Loopback)        RX packets 39007 bytes 27010089 (27.0 MB)        RX errors 0 dropped 0 overruns 0 frame 0        TX packets 39007 bytes 27010089 (27.0 MB)        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0ppp0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1492        inet 114.xxx.xxx.xxx netmask 255.255.255.255 destination 168.95.98.254        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 fe80::xxxx:xxxx:xxxx:xxxx prefixlen 128 scopeid 0x20<link>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        inet6 2001:b011:14:410a:xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x0<global>        ppp txqueuelen 3 (Point-to-Point Protocol)        RX packets 1004452 bytes 224455771 (224.4 MB)        RX errors 0 dropped 0 overruns 0 frame 0        TX packets 954499 bytes 990512298 (990.5 MB)        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0