The hardware resources required by the gateway vary based on the type of connection (import versus live connection), the usage of the reports and dashboards in the Power BI service, and the proportion of data volume handled by the gateway versus the on-premises source systems. It's recommended to start with eight-core CPUs with an 8 GB of RAM server. This machine cannot be a domain controller, and to maintain availability of Power BI content, the gateway server should be always on and connected to the internet.
Based on an analysis of current and projected workloads, the gateway resources can be scaled up or down and optionally additional gateways can be installed on separate servers to distribute the overall Power BI refresh and query deployment workload. For example, one gateway server can be dedicated to scheduled refresh/import workloads, thus isolating this activity from a separate gateway server responsible for DirectQuery and Live Connection queries.
The gateway does not require inbound ports to be opened and defaults to the outbound port of TCP 443, 5671, 5672 and 9350 through 9354. The gateway can be forced to use HTTPS communication exclusively and avoid the use of IP addresses via both the UI and the configuration files directly but this may impair performance. For the default communication mode, it's recommended to whitelist the IP addresses in your data region in your firewall. This list is updated weekly and is available via the Microsoft Azure Datacenter IP list (http://bit.ly/2oeAQyd).