Symptoms

You receive a warning about self signed certificate when you open RAS HTML5 Gateway in browser.
HALBs are used for SSL load balancing and configured in SSL Offloading mode, you have set up 3rd party SSL certificate for that.
When you check certificate properties in web browser, you can see that it is issued to www.2x.com by www.2x.com instead of your FQDN and 3rd party CA:

Cause

It's a known issue with HALBs version 17.0.21282. Parallels Engineering team is aware of it and is working on fix.

Resolution

There are two possible workarounds:

1. Install the certificate on each Gateway and then reconfigure HALBs in Passthrough mode:
   
   
   Please refer to page 65 of Administrator's guide for instructions on Gateway configuration.
    
2. Replace HALB appliances version 17.0.21282 with appliances version 16.5.3.20735. They are backward compatible with RAS 17 and can be downloaded using the links below:
   HALB Appliance OVA
   HALB Appliance VHD
   HALB Appliance VMDK