Unknown error 116 running the test

[mreid-tt]

Symptom

When running the iPerf3 test with the default configuration (5 streams and 30s) the test runs fine. However when I increase the duration to 5 min, the test eventually gives the error "Unknown error 116 running the test" for more than half of the test runs and does not complete. This happens whether in 'Upload' or 'Download' transmit mode.

Client

Model Name: iPad (6th generation)
Software Version: iOS 14.3
iPerf 3 WiFi Speed Test Version: 3.6.11

Server

Model Name: Synology VirtualDSM
CPU: INTEL Pentium N3710
DSM Version: DSM 6.2.3-25426 Update 3
Software Version: iperf 3.9 (cJSON 1.7.13)

Server Log

admin@Demo-NAS:/$ iperf3 -s
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from YY::YY:YY:YY:YY, port 57705
[  5] local XX::XX:XX:XX:XX port 5201 connected to YY::YY:YY:YY:YY port 57706
[  8] local XX::XX:XX:XX:XX port 5201 connected to YY::YY:YY:YY:YY port 57707
[ 10] local XX::XX:XX:XX:XX port 5201 connected to YY::YY:YY:YY:YY port 57708
[ 12] local XX::XX:XX:XX:XX port 5201 connected to YY::YY:YY:YY:YY port 57709
[ 14] local XX::XX:XX:XX:XX port 5201 connected to YY::YY:YY:YY:YY port 57710
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  9.85 MBytes  82.5 Mbits/sec                  
[  8]   0.00-1.00   sec  11.0 MBytes  91.8 Mbits/sec                  
[ 10]   0.00-1.00   sec  10.5 MBytes  88.2 Mbits/sec                  
[ 12]   0.00-1.00   sec  11.0 MBytes  92.2 Mbits/sec                  
[ 14]   0.00-1.00   sec  10.6 MBytes  88.5 Mbits/sec                  
[SUM]   0.00-1.00   sec  52.9 MBytes   443 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[Results - Approximately 140 sets]
- - - - - - - - - - - - - - - - - - - - - - - - -
[  5] 146.00-147.00 sec  9.95 MBytes  83.5 Mbits/sec                  
[  8] 146.00-147.00 sec  9.52 MBytes  79.9 Mbits/sec                  
[ 10] 146.00-147.00 sec  10.0 MBytes  83.9 Mbits/sec                  
[ 12] 146.00-147.00 sec  9.63 MBytes  80.7 Mbits/sec                  
[ 14] 146.00-147.00 sec  9.89 MBytes  82.9 Mbits/sec                  
[SUM] 146.00-147.00 sec  49.0 MBytes   411 Mbits/sec                  
iperf3: the client has unexpectedly closed the connection
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------

[ndfred]

No clue as to why that happens, I have an iPerf 3.9 client coming (need to sort out my Apple certs before I can update) that might help since your server is iPerf 3.9 as well. Error 116 is IESENDRESULTS Unable to send results to client/server (check perror), I could try and surface perror to help diagnose issues like this:
https://github.com/ndfred/iperf-ios/blob/master/Source/iperf3/iperf_api.h#L381

[supersophie]

Hi,
I got this when trying to connect to a iperf3 server running on Macos ( iperf -s)

unknown error 113 running test.

followed by

unknown error 116 running test.

Macos server displayed :

iperf3: error - unable to set TCP/SCTP NODELAY: Invalid argument

Server details:

iperf 3.17.1 / Darwin 21.6.0