Instances are in Red or Yellow state on NetScaler MAS.

Complete the following steps to troubleshoot this issue:

• Examine the /var/mps/log/mps_inventory.log, if there are any NITRO or PING failure for such NetScaler Instances.
  Check mps_config.log as well from same directory path for errors while adding the NS to ADM

• Verify network reachability from NetScaler MAS to NetScaler Instances. Use tcpdump on NetScaler MAS.

• Verify NetScaler profile user and password to login to NetScaler. Click on Instance or EDIT option and check the selected Profile
  
  Try using default username password on NS and set that as a profile on ADM and reconnect again.

• Check the method that MAS will use to communicate with NetScaler. Your NetScaler might only listen to HTTPS. Go to SYSTEM > CHANGE SYSTEM SETTINGS.

• Ensure the NetScaler instances are reachable from NetScaler MAS server.

• Ensure that NetScaler MAS NITRO and ping are able communicate with NetScaler instances.

• Ensure that NetScaler password is not out of sync with instance password.

• Ensure that HTTP is not disabled in NetScaler but configured to use this in profile.