OpenWRT 随机断网解决方案

百善孝为先，论心不论迹，论迹贫家无孝子；
万恶淫为首，论迹不论心，论心世上少完人。

——《围炉夜话》清/王永彬

最近折腾便宜小巧软路由 R2S ,安装 OpenWRT 系统后时不时的连接失败，最终查明原因，贴出解决方案。

一、问题

• 表征问题： 随机断网，ubuntu 网络接口小问号。
• 物理设备： R2S 主路由，接 NETGEAR GS308 8口千兆交换机，接无线路由。
• 系统日志：

  Wed Nov 25 20:28:54 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:28:54 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:28:59 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:28:59 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:04 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:29:04 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:10 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:29:10 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:15 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:29:15 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:22 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:27 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.114.114" on interface wan (eth0)
  Wed Nov 25 20:29:27 2020 user.info mwan3track[24520]: Check (ping) success for target "114.114.115.115" on interface wan (eth0)
  Wed Nov 25 20:29:27 2020 user.info mwan3track[24520]: Lost 1 ping(s) on interface wan (eth0)

二、解决方案

负载均衡 MWAN3 设置错误，是 MWAN3 这里的检测端口是否在线的 DNS 被墙了，3次 ping 失败就认为端口离线了，换成国内的 DNS 或者把检测开关关掉。

在网络-负载均衡下修 WAN 口设置，跟踪的主机或 IP 地址为国内 DNS 。或直接不启用。或直接删除 WAN 口设置。

跟踪的主机或 IP 地址为阿里 DNS 223.5.5.5 后日志显示如下：

Wed Nov 25 20:56:31 2020 user.notice mwan3rtmon[4274]: Stopping mwan3rtmon...
Wed Nov 25 20:56:33 2020 user.notice mwan3track[24308]: Stopping mwan3track for interface "wan"
Wed Nov 25 20:56:45 2020 user.notice mwan3[31357]: Using firewall mask 0x3F00
Wed Nov 25 20:56:45 2020 user.notice mwan3[31357]: Max interface count is 60
Wed Nov 25 20:56:46 2020 user.notice mwan3[31357]: Execute ifup event on interface wan (eth0)
Wed Nov 25 20:56:46 2020 user.notice mwan3[31357]: Starting tracker on interface wan (eth0)
Wed Nov 25 20:56:47 2020 user.notice firewall: Reloading firewall due to ifup of wan (eth0)
Wed Nov 25 20:56:57 2020 user.notice mwan3[32104]: Execute ifdown event on interface wan (eth0)
Wed Nov 25 20:56:58 2020 user.info mwan3track[31660]: Detect ifdown event on interface wan (eth0)
Wed Nov 25 20:57:03 2020 user.notice mwan3track[31660]: Interface wan (eth0) is offline
Wed Nov 25 20:57:03 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)
Wed Nov 25 20:57:08 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)
Wed Nov 25 20:57:13 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)
Wed Nov 25 20:57:18 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)
Wed Nov 25 20:57:24 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)
Wed Nov 25 20:57:29 2020 user.info mwan3track[31660]: Check (ping) success for target "223.5.5.5" on interface wan (eth0)