I was configuring iSCSI targets using tgt / tgtd on Ubuntu Server 18.04 and wanted to connect to them from a windows machine. Linux machines could connect without issues already so I did not expect any problems. Well... the windows machines did not connect with the error "The target name is not found or is marked as hidden from login.", which was quite cryptic. After checking the configuration over and over and testing on and from multiple other machines, I finally found the problem.
[Solution]
The target string MUST NOT contain upper-case letters! I had:
iqn.2018-06.domain.reverse.my:My-Target-Name
This will not work, while the following WILL work:
iqn.2018-06.domain.reverse.my:my-target-name
Everything is connecting and working like a charm now
