Please check the MTU value for uplink and downlink for your host/nodes. It relates to maximum frame size that can be transported on the data link layer, e.g. Ethernet frame.
Verify the configuration across switches connecting the nodes across the cluster.
Ideally the frame size is 1500 bytes /sec & to provide maximum data transfer the jumbo buffers can be enabled (based on hardware configuration ) ensuring faster data transmission @ 9000 bytes/sec.