This is probably related to Origin checking. https://docs.vmware.com/en/VMware-Horizon/2106/horizon-security/GUID-94DAC7B8-70A3-4A91-8E70-2B2591B...
What entries do you have in the locked.properties file? (Note that you have to create this file)
To test this:
- You can turn off Origin checking by adding checkOrigin=false to locked.properties.
- If this is running Horizon 8 2106 then Cross Origin Checking will be enabled by default. You can add enableCORS=false as well to turn that off.
Ideally you should be leaving those on though, so only do the above as a test to prove it is origin checking causing this. You should then remove them and look to add the following entries instead:
- balancedHost = <load balancer FQDN>
- portalHost.1=<uag1 FQDN>
- portalHost.2=<uag2 FQDN>
