Problem:
When running iperf -c [IP address]
you see this error message:
connect failed: Operation in progress
Solution:
You are running different iperf versions on the server and the client. Typically this error occurs if the client is running iperf
2.x whereas the server is running iperf
3.x.
Check using iperf --version
. In my case, on the client, it was
iperf version 2.0.13 (21 Jan 2019) pthreads
on OpenWRT.