Ciao
I'm trying to understand your infrastructure.
Do your users need to access the Horizon infrastructure from outside (from the internet) or are they just users of your network?
What version of Horizon do you have?
Do you have only one connection server or do you have more? if you have more how do you manage the balance?
Why are you talking about port 3088 in point 5?
Is the certificate you use for a public FQDN or connection server name?
If you want to use access from outside your corporate network, I recommend using UAGs (Unified Access Gateways)
You can post the screenshot of the error?
