The testsuite/integration/multinode suite includes two servers. Tests do various manipulations of those servers and use the ServerReload.reloadIfRequired utility to attempt to reload the servers if necessary.
The problem is the behavior of the ServerReload.reloadIfRequired(ModelControllerClient) method is to use TestsuiteEnvironment to get the address/port of the server to connect to after the reload in order to poll waiting for completion of the reload. But that breaks down in multi-server environments as TestsuiteEnvironment is going to only provide the data for one of the servers, so ServerReload is not going to accurately wait for completion of reload for the other.
ServerReload provides an overloaded reloadIfRequired method where a ManagementClient instead of a ModelControllerClient can be provided. If that is used then the correct address/port is taken from the ManagementClient. So that variant should be used wherever possible.