Here is sample error,

Unhandled AutoservRunError: Timeout encountered: /usr/bin/ssh -a -x -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o BatchMode=yes -o ConnectTimeout=30 -o ServerAliveInterval=900 -o ServerAliveCountMax=3 -o ConnectionAttempts=4 -o Protocol=2 -l root -p 22 android1758-row4-rack5-host1 "export LIBC_FATAL_STDERR_=1; if type \"logger\" > /dev/null 2>&1; then logger -tag \"autotest\" \"server[stack::warmup_stations|warmup_wifi_part|run] -> ssh_run(/usr/local/bin/netperf -H 192.168.0.254 -p 12865 -t TCP_STREAM -l 2 -- -P 0,12866)\";fi; /usr/local/bin/netperf -H 192.168.0.254 -p 12865 -t TCP_STREAM -l 2 -- -P 0,12866" 

More logs @
https://wmatrix.googleplex.com/unfiltered?suites=wifi_perf&tests=network_WiFi_Perf.ht40_aes,network_WiFi_Perf.ht40&days_back=20&releases=55&platforms=cyan

https://wmatrix.googleplex.com/unfiltered?suites=wifi_perf&tests=network_WiFi_Perf.ht40_aes,network_WiFi_Perf.ht40&days_back=20&releases=54&platforms=cyan