I'm going to look into this a bit more, but I want to be clear: this isn't a trooper bug. A test suite taking too long is a test problem.

I was suspecting that the suit got stuck because of networking issues.

Is there something in the logs that'd make you suspect that?

No, I am not familiar with this suit, so just a wild guess + I know that
windows bots were affected by networking issues + there is "net" in suit
name. Looked like it's attempting to start the next shard, but then there
is no output from tests from that shard.

Looking at the first and last failures this is flaky timeout in NetworkErrorLoggingEndToEndTest.UploadAtShutdown which has been disabled in https://bugs.chromium.org/p/chromium/issues/detail?id=820950 so I'm marking this as a dup.

  880.774s run_tests_on_device(04d457720061f2ba)  Still working on StartInstrumentation(04d457720061f2ba, org.chromium.native_test/org.chromium.native_test.NativeTestInstrumentationTestRunner, retries=0, extras={'org.chromium.native_test.NativeTestInstrumentationTestRunner.ShardNanoTimeout': 300000000000, 'org.chromium.native_test.NativeTestInstrumentationTestRunner.NativeTestActivity': 'org.chromium.native_test.NativeUnitTestActivity', 'org.chromium.native_test.NativeTest.RunInSubThread': 1, 'org.chromium.native_test.NativeTestInstrumentationTestRunner.Test': 'NetworkErrorLoggingEndToEndTest.UploadAtShutdown', 'org.chromium.native_test.NativeTestInstrumentationTestRunner.StdoutFile': '/storage/emulated/legacy/temp_file-2878fef51cd2b.gtest_out'}, timeout=300.0, raw=False)


I  878.549s run_tests_on_device(07e4d08e0075f229)  Still working on StartInstrumentation(07e4d08e0075f229, org.chromium.native_test/org.chromium.native_test.NativeTestInstrumentationTestRunner, retries=0, extras={'org.chromium.native_test.NativeTestInstrumentationTestRunner.ShardNanoTimeout': 300000000000, 'org.chromium.native_test.NativeTestInstrumentationTestRunner.NativeTestActivity': 'org.chromium.native_test.NativeUnitTestActivity', 'org.chromium.native_test.NativeTest.RunInSubThread': 1, 'org.chromium.native_test.NativeTestInstrumentationTestRunner.Test': 'NetworkErrorLoggingEndToEndTest.UploadAtShutdown', 'org.chromium.native_test.NativeTestInstrumentationTestRunner.StdoutFile': '/storage/emulated/legacy/temp_file-5903c795ca304.gtest_out'}, timeout=300.0, raw=False)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aed5ad2b6f9f164093832f5590647f90a94f74fb

commit aed5ad2b6f9f164093832f5590647f90a94f74fb
Author: Matt Menke <mmenke@chromium.org>
Date: Tue Mar 20 16:16:13 2018

Make fewer connections in PacFileFetcherImplTest.IgnoresLimits.

It was making enough connections to exceed the total socket pool limit,
which is currently 256, and apparently large enough to cause timeouts on
some bots.  Switch to using the per-group limit instead - socket pool
tests themselves should make sure that ignore_limits ignores the global
pool limits as well, as there's no other way to exceed the per-group
limit, so just checking the per-group limit should be sufficient.

Bug:  820845 
Change-Id: I2a661b535492c5bbca4e90710bd2d91e6115edfe
Reviewed-on: https://chromium-review.googlesource.com/964542
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Eric Roman <eroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544391}
[modify] https://crrev.com/aed5ad2b6f9f164093832f5590647f90a94f74fb/net/proxy_resolution/pac_file_fetcher_impl_unittest.cc