The latency setting is not accurate in clumsy.

[StephensCheng]

I use the WANem to set the network latency, and use ping command to monitor the RTT value. (I only set the latency is 10ms).
The RTT value is about 20ms;

At the same time, I use the clumsy to set the network latency, use the ping command to monitor the RTT value.(only set the latency is 10ms)
The RTT value fluctuates in a large range;

The background network condition is great, basic RTT is 2ms -5ms.

[AloisKraus]

I also see the same behavior. When I enable Latency with a 0 ms delay I find in Wireshark already a 20ms up to 75ms latency added by clumsy. That latency also fluctuates quite a bit.

Latency enabled

Latency disabled

[tourist1584970446]

getting same results, even completely local! Up to +80ms
turned on [x] Lag with 0ms outbound

Reply from 127.0.0.1: bytes=32 time=54ms TTL=128
Reply from 127.0.0.1: bytes=32 time=34ms TTL=128
Reply from 127.0.0.1: bytes=32 time=15ms TTL=128
Reply from 127.0.0.1: bytes=32 time=79ms TTL=128
Reply from 127.0.0.1: bytes=32 time=28ms TTL=128
Reply from 127.0.0.1: bytes=32 time=81ms TTL=128
Reply from 127.0.0.1: bytes=32 time=22ms TTL=128
Reply from 127.0.0.1: bytes=32 time=19ms TTL=128
Reply from 127.0.0.1: bytes=32 time=12ms TTL=128
Reply from 127.0.0.1: bytes=32 time=61ms TTL=128
Reply from 127.0.0.1: bytes=32 time=21ms TTL=128
Reply from 127.0.0.1: bytes=32 time=8ms TTL=128
Reply from 127.0.0.1: bytes=32 time=50ms TTL=128
Reply from 127.0.0.1: bytes=32 time=59ms TTL=128
Reply from 127.0.0.1: bytes=32 time=11ms TTL=128
Reply from 127.0.0.1: bytes=32 time=59ms TTL=128
Reply from 127.0.0.1: bytes=32 time=73ms TTL=128
Reply from 127.0.0.1: bytes=32 time=55ms TTL=128

turned off [ ] Lag

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

it behaves the same for ipv6 btw