EdgeRouter 默认 RDNSS Lifetime 过短导致 iOS 设备唤醒时优先使用移动数据

这两天把家里 DNS 改成 RA 下发, 遇到了标题上的问题

使用 radvdump, 输出为:

interface switch0

{

        AdvSendAdvert on;

        # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump

        AdvManagedFlag off;

        AdvOtherConfigFlag off;

        AdvReachableTime 0;

        AdvRetransTimer 0;

        AdvCurHopLimit 64;

        AdvDefaultLifetime 1800;

        AdvHomeAgentFlag off;

        AdvDefaultPreference medium;

        AdvSourceLLAddress on;



        prefix [GUA Prefix]

        {

                AdvValidLifetime 2592000;

                AdvPreferredLifetime 604800;

                AdvOnLink on;

                AdvAutonomous on;

                AdvRouterAddr off;

        }; # End of prefix definition





        prefix [ULA Prefix]

        {

                AdvValidLifetime 2592000;

                AdvPreferredLifetime 604800;

                AdvOnLink on;

                AdvAutonomous on;

                AdvRouterAddr off;

        }; # End of prefix definition





        RDNSS [DNS]

        {

                AdvRDNSSLifetime 600;

        }; # End of RDNSS definition



}; # End of interface definition

默认为 600 秒, 显然是太短了, 息屏超过十分钟 DNS 过期, 导致唤醒时优先使用移动数据. EdgeOS 没有提供内置的 RDNSS Lifetime 节点, 但是可以设置 radvd-options "RDNSS [DNS] { AdvRDNSSLifetime 86400; };" 来解决这个问题, 注意要删除 name-server 节点.

修正后的 radvdump 输出:

interface switch0

{

        AdvSendAdvert on;

        # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump

        AdvManagedFlag off;

        AdvOtherConfigFlag off;

        AdvReachableTime 0;

        AdvRetransTimer 0;

        AdvCurHopLimit 64;

        AdvDefaultLifetime 1800;

        AdvHomeAgentFlag off;

        AdvDefaultPreference medium;

        AdvSourceLLAddress on;



        prefix [GUA Prefix]

        {

                AdvValidLifetime 2592000;

                AdvPreferredLifetime 604800;

                AdvOnLink on;

                AdvAutonomous on;

                AdvRouterAddr off;

        }; # End of prefix definition





        prefix [ULA Prefix]

        {

                AdvValidLifetime 2592000;

                AdvPreferredLifetime 604800;

                AdvOnLink on;

                AdvAutonomous on;

                AdvRouterAddr off;

        }; # End of prefix definition





        RDNSS [DNS]

        {

                AdvRDNSSLifetime 86400;

        }; # End of RDNSS definition



}; # End of interface definition

如果你最近遇到了类似的问题, 可以参考一下.