Limit upload bandwidth and the client cannot access the network

[wfj1216]

platform:OpenWRT, X86,
linux kernel:3.18.45
I follow README and put the code on openwrt, compile and load.
Configuration commands are as follows:
ipfw add pipe 2 ip from any to 172.10.0.0/16
ipfw pipe 2 config mask dst-ip 0xffffffff bw 10Mbit/s buckets 256
I test download bandwidth, it's normal.

But when I restrict the upload bandwidth, the client cannot access the network.
Configuration commands are as follows:
ipfw add pipe 3 ip from 172.10.0.0/16 to any
ipfw pipe 3 config mask src-ip 0xffffffff bw 1Mbit/s buckets 256

Please help to repair this problem, thank you.