Don’t do a me and not schedule a maintenance window when adjusting/removing storage pools on a QNAP NAS when you have active iSCSI connections.
I had a TS-1273U-RP with 2 storage pools configured, one with a block-based thick LUN and another with just folder shares. Deleting the second folder shares pool caused the thing to drop the iSCSI connection from a Hyper-V host to the first pool and wouldn’t reconnect until it was restarted.
Make sure you schedule a window and be prepared to lose the iSCSI connections until you reboot after removing the pool(s).
All fun on a Friday…