1. Create a Horizon deployment that spans multiple sites, or supports more connections than are possible with a single pod.
2. 10.
3. 25.
4. Global Entitlement.
5. Yes.

6. Use the Horizon home site resolution tool.
7. The pod where the connection originated from.
8. The pool you are trying to add does not use the same settings as the Global Entitlement, such as floating or dedicated assignment.