The issue described is generally clear, yet nothing is said about the NIC vendor and the exact model in use (PCI IDs from lspci output would be ideal). The use of the bucket mempool already rings a bell as it is known to be used on a specific datapath implementation of one of the NIC vendors, yet the user can enforce a specific mempool type at build time, so it would be better to clarify whether it's indeed the said vendor-specific case or the OP has enabled "bucket" themselves.