No IPv6 connectivity after waking up from sleep

I am having issues with IPv6 connectivity on El Capitan (and many previous version)

Waking my Mac up from sleep I immediately get IPv4 connectivity.

I do also get an IPv6 address and learn my gateway via IPv6 ND and SLACC.

There was a thread for Mavericks by someone else who had a similar issue, but no real solution: No IPv6 after wake from sleep

$ ping6 google.de

PING6(56=40+8+8 bytes) 2003:de:4bc9:dc00:199a:edff:5214:e01 --> 2a00:1450:4001:816::2003^C

--- google.de ping6 statistics ---

7 packets transmitted, 0 packets received, 100.0% packet loss

$ ifconfig en0

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500

ether 60:03:08:8d:ac:e2

inet6 fe80::6203:8ff:fe8d:ace2%en0 prefixlen 64 scopeid 0x4

inet 10.1.16.131 netmask 0xffffff00 broadcast 10.1.16.255

inet6 2003:de:4bc9:dc00:6203:8ff:fe8d:ace2 prefixlen 64 autoconf

inet6 2003:de:4bc9:dc00:199a:edff:5214:e01 prefixlen 64 autoconf temporary

$ netstat -nrf inet6

Routing tables

Internet6:

Destination Gateway Flags Netif Expire

default fe80::3631:c4ff:fefd:da7%en0 UGc en0

[...]

$ ping6 fe80::3631:c4ff:fefd:da7%en0

PING6(56=40+8+8 bytes) fe80::6203:8ff:fe8d:ace2%en0 --> fe80::3631:c4ff:fefd:da7%en0

16 bytes from fe80::3631:c4ff:fefd:da7%en0, icmp_seq=0 hlim=64 time=2.158 ms

16 bytes from fe80::3631:c4ff:fefd:da7%en0, icmp_seq=1 hlim=64 time=1.937 ms

^C

--- fe80::3631:c4ff:fefd:da7%en0 ping6 statistics ---

2 packets transmitted, 2 packets received, 0.0% packet loss

round-trip min/avg/max/std-dev = 1.937/2.047/2.158/0.110 ms

Aand just a few seconds later it magically works again and my gateway and ipv6 address are still the same:

$ ping6 google.de

PING6(56=40+8+8 bytes) 2003:de:4bc9:dc00:199a:edff:5214:e01 --> 2a00:1450:4001:816::2003

16 bytes from 2a00:1450:4001:816::2003, icmp_seq=0 hlim=57 time=13.160 ms

16 bytes from 2a00:1450:4001:816::2003, icmp_seq=1 hlim=57 time=10.449 ms

^C

--- google.de ping6 statistics ---

2 packets transmitted, 2 packets received, 0.0% packet loss

round-trip min/avg/max/std-dev = 10.449/11.805/13.160/1.355 ms

It really is a shame that apple has not yet fixed this as more and more sites get ipv6 enabled, which leads to basically no connectivity for the first seconds/minutes after wakeup from sleep.