Did you ever see the movie Holes (2003)?

Honestly depends on whats being served. As i say people can run servers on enterprise grade multi thousand £ systems or a £50 pi or mini pc.

Since you have a specific usage in mind, media server, you basically want hardware that will allow optimised performance so you can have a lag/ buffer free experience.

Say,

hardware thats good for on the fly encoding/ decoding

Lots of ram for multitasking.

Lots of storage to store the media.

Maybe gigabit network cards for multiuser streaming without bandwidth bottlenecks.

It really depends on the experience and chokepoints

ECC ram ill let someone more familiar answer but im leaning towards non critical and nice to have

Nothing you couldnt upgrade on your typical PC. Just makes life easier…at a cost.

Server serves a specific application(s). PC is general day to day usage.

Both are computers. Pc hardware can be used as a server. Server hardware can be used as a pc.

Using a computer for day to day tasks - call it a pc. Use it to run a web server application or host a game - that one or more users will access - call it a server

Hardware can be configured to optimise it for its function. E.g pc can have latest GPUs and “servers” can have multicore cpus and loads of ram, rack mounting form factor and dual power supplies for redundancy.

But it could also be weak - i have raspberry pi’s and old laptops set up as a servers

Check out PrivacyGuides. They have recommendations for DNS including what others have commented

Many selfhosted NVRs have been suggested. Personally ive tried:

iSpy

Frigate

Zoneminder

Shinobi

Ended up settling on zoneminder at this stage.

For cameras themselves i just want to point out the OpenIPC project - opensource firmware if youre technically inclined

Edit: I’m hesitant to recomment OpenIPC now since the main streamer is closed source. Thingino is fully open and developed by some of the devs who didn’t agree with the closed source portion