diff --git a/etc/startup-config.default b/etc/startup-config.default
index 82bb1c8..496522e 100644
--- a/etc/startup-config.default
+++ b/etc/startup-config.default
@@ -158,3 +158,6 @@ set ppp_keepalive yes
 #
 # and allow dhcpv6 traffic:
 # iptables -A INPUT -i ppp+ -p udp --sport 546 --dport 547 -j ACCEPT
+#
+# and increase the memory available for igmp6 for DHCPv6 and RS:
+# sysctl net.core.optmem_max=10485760