"iperf3: error - unable to read from stream socket: Resource temporarily unavailable" after running PTP4l

# Context

* Version of iperf3: Iperf 3.1.1

* Hardware: macB cadence, Power PC E550

* Operating system (and distribution, if any): Linux 4.1.38

# Bug Report

* Expected Behavior
I am trying to make iperf3 work with PTP4l at the same time, I expect to have clock synchronization while testing the network bandwidth.

* Actual Behavior
When running iperf3 without running ptp4l I get a successful network test:

Then, If I run PTP4l, I can have the clocks synchronization working:

If I try to run iperf3 again, I got "iperf3: error - unable to read from stream socket: Resource temporarily unavailable":

Running tcpdump I see one pattern:

This is the server side, on the left the capture before running PTP4l, on the rigth after running PTP4l

This is the client side, on the left the capture before running PTP4l, on the rigth after running PTP4l. In this capture I see:
-In the left side a message is sent from the client to the server, then appear the "Connecting to host..." msg, and finally a second message is sent from the client to the server.
-In the rigth side a message is sent from the client to the server, then a second message is sent from the client to the server, and finally appear the "Connecting to host..." msg.

I always see this pattern when running ptp4l.


* Steps to Reproduce
-Run Iperf3
-Run PTP4l
-Run again Iperf3

Can someone help me to find the reason for this? or maybe give me some guidance to try to figure out why I am getting this issue?

Best regards