Configuring Synology for iSCSI ESXi host access

Unlike NFS by default iSCSI support is enabled,  first step to configure is to use Storage Manager,  change to iSCSI LUN and click create

Use wizard to give the LUN a name,  specify which volume it will reside, whether you want it thick, and its size, if this is your first iSCSI LUN ensure iSCSI target mapping is Create a new iSCSI target

Leave all defaults for target

Once completed,  edit the new target and ensure all LUNs are mapped which you would want to present to ESXi

If you now create a iSCSI adapater and point it to the Synology IP to dynamically discover the LUNs as shown here.