This is what NAS 2 is stating for the LUNs:
initiator:iqn.1998-01.com.vmware:esxi4-50e6a774
ip:172.30.1.16
state:active
Which is the same on NAS 1 where it is working. And as I said: When I configure "send targets", it automatically shows three targets in the static targets config, with the correct names, so at least something must be working.