As per the release notes of Horizon 8.2:

The forwarding rules for HTTP requests received by Connection Server instances have changed at this release. If you have defined custom frontMapping entries in locked.properties, you should remove them before upgrading. If you wish to disallow administrator connections to certain Connection Server instances, then instead of defining custom frontMapping entries, add this entry to locked.properties:
frontServiceWhitelist = tunnel|ajp:broker|ajp:portal|ajp:misc|moved:*|file:docroot

Also you can use the KB: https://kb.vmware.com/s/article/2088354