How do I change the bulk size of a get/post queue on the primary hub and the related attach queue on the secondary hub?
You can change the bulk size of the GET queue on the Primary hub via the hub probe GUI -> Queues -> right-click on the Get - queue -> edit and change the Bulk Size to the desired value. The attach queue on the secondary hub will then take the bulk size from the Get queue that is draining the messages. Leave the ATTACH queue as is.