UniFi is an ecosystem of wireless access points, routers, switches, security cameras, controller appliances, VoIP phones, and access control products. UniFi exists somewhere between enterprise and cheap home networking gear. It’s a nice middle ground, offering more flexibility and features than AmpliFi, but lacking the expense, licensing, and complexity of enterprise-grade equipment.
With a typical UniFi network, you chose which parts you want, and how many of them. You can start small with one access point, or go all out and get everything.
The UniFi controller software is what ties it all together, giving you a web interface (and mobile app) to configure everything. The controller software is only required for configuration. UniFi devices will continue to work without it running. However, a lot of the benefits (monitoring, logging, statistics, etc.) of UniFi require an always-on controller. You should plan to have one, and there are a few ways to do that.
The controller software can be self-hosted, or run on dedicated hardware Ubiquiti makes, called a Cloud Key. The CloudKey Gen2 and Gen2+ are the current models. The Gen2+ adds a hard drive bay, and can act as a NVR for their camera system, UniFi Protect. Your camera footage would be stored on the hard drive in the CloudKey Gen2+.
You also have the option of running the UniFi controller software on any PC you have, on a physical server, or in a VM or Docker container. A lot of people suggest Docker as the way to go if you want to self-host. It's a great use for a Raspberry Pi.
UniFi equipment will work with other vendor's equipment, but you'll have at least two different systems to control. A lot of people like to add UniFi wireless access points to their existing switches and routers, and that's a good way to get started. You don't need to the full UniFi stack, but there are benefits to it.
By the way, you can check the products of UBNT.
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