Requirements:
-4 Cores CPU is the minimum to handle 1k players
-10GB of RAM for every 1k players
-100BM/s Internet is the minimum for good ping
-20GB Storage is enough for server files and tools, etc..
-Windows Server +Sql Server is the default work environment (previous versions like 2008 is good and faster but, people can bypass firewall scopes and RDP)
-1 town or 1 GameServer can't handle more than 1k players
-3500 player +400 vip is the maximum players...