补充条刚看到的国外用户博客，同时再次感谢楼上热心的朋友们

I was reminded by Apple product managers a few months ago while talking about AirPort issues that the lower band uses 1/20th the power of the upper band. That's right: Choose channel 149, and your base station broadcasts signals at 20 times the power of channel 36! (The 5 GHz band, because of its shorter wavelength, requires more power to send the same quantity of data the same distance as a 2.4 GHz device.)

@TashinV 非常感谢！改完后，确实恢复了全速。之前都是默认路由器的“自动”，没想到这个 channel 影响如此之大。

@deepjia 仍然不太理解。除了手机的蓝牙，家里没有蓝牙源，关了手机的蓝牙，也是这个速度。

@iCruiser 重启过，没有效果。而且手机测，全速。
TX Rate:600 Mbps 稳定， Channel:36 5Ghz, 就在路由器所在房间 2 米无遮挡。

@gracece 朋友，没明白您的意思

@suduo1987 更新完IOS，运营商系统已经从18.0变成19.0，显然过程中自动更新了