ESXi 6.5 fails to Discover or Connect to a Synology iSCSI Target with CHAP Authentication

If you are having trouble getting ESXi to discover a Synology iSCSI target with CHAP authentication, check your vobd log for errors that may look similar to the below:

This basically confirms some kind of problem negotiating the CHAP authentication. After double checking that you are using the correct CHAP credentials and you are still not able to get the ESXi host to discover the Synology target, try the steps below:

  1. In the Synology Storage Manager for iSCSI Target, first disable Mutual CHAP (if enabled) and check that CHAP is enabled.
    Then in ESXi Configure iSCSI as follows:
  2. Set only a Dynamic Target using the IP address and port of the Synology target. Remove any Static Target that you may have set.
  3. Temporarily set CHAP Authentication to “Do not use CHAP”
  4. Set Mutual CHAP Authentication to “Do not use CHAP”
  5. Click Save Configuration
  6. Click Refresh on the Devices tab and confirm the Synology is not being discovered
  7. Now go back the iSCSI configuration in ESXi
  8. Set CHAP Authentication back to “Use CHAP”
  9. Click the down arrow and enter your CHAP credentials
  10. Confirm the Static Target is now populated with the Synology target address information. If not, try populating it now.
  11. Click Save Configuration
  12. Click Refresh on the Devices tab

The Synology target should then show up in ESXi.