Just updates 2 routers to 1.3.0 build today.
The image includes iperf 2.0.12.
When doing performance test with -d for both directions i get
write failed: Connection reset by peer
This seems to be an issue in version 2.0.12, fixed in 2.0.13a.
https://sourceforge.net/p/iperf2/discussion/general/thread/cb147b7a1d/