Why logging in to an iSCSI target can be slow sometimes?
It is caused by wrong IP address in portal window.
For iSCSI target that was created with option to not inherit from global settings, please edit targets portal settings by right clicking on the target, selecting properties, switching to portal tab and changing portal IP there.
For iSCSI targets with selected option to inherit from global settings, open settings as described above and access portal window.
Then check if there is any IP address which client can’t use and remove it from the list.