When I'm walking to a nearby place, why the WiFi speed become very slow in a sudden?

Usually, it is because your cellphone still connects to the original place's wireless device. Since you are not far away from it, the signal become weak but still connected. This will cause the wireless network being unstable.
Solution: Please be patient and wait for the cellphone to automatically detect and connect to the nearest wireless device. Or, manually disconnect WiFi on your cellphone and then reconnect

问: 当我去不远处的会议室开会或从在图书馆从一个地方走到不远处的另一个地方时,手机WIFi忽然变得特别慢。
答: 这种情况往往是因为你的手机网络连接的还是原来的地方的无线设备,你走的不远,信号已经变得微弱但没有断开,造成无线网络不稳定。
解决方法: 耐心等待手机网络自动探测和连接到最近的无线设备或直接手动断开手机的WIFI并再次连接。