Currently create_suite_job RPC has code like:

ds = dev_server.resolve(test_source_build)
...
(ds, keyvals) = _stage_build_artifacts(test_source_build)

The devserver_url is passed to the hostless job and eventually used by test. These calls doesn't care where devserver is located even if global config prefer_local_devserver is set to True.

For prefer_local_devserver to work as expected, create_suite_job should try to locate a devserver inside the same subnet if prefer_local_devserver is set to True. One way to do this is to pick a host based on pool and board arguments of create_suite_job call. And use that host to locate devserver. Likely hosts with same board and pool are in the same lab.

This needs to be done before ACL can be applied to each lab.