Nvr with a POE switch is the way to go. Nvr's provide it's own bandwidth to cover the cameras with little to no effect on you network. Unless you start changes settings. I suggest running Cat 6 for your internet on the NVR and switch(faster communication) and Cat 5e to your cams will be just fine. I would go with 4k cams in HD and trust me you'll love the clearity. I got my system on a mesh network and hardly no delays or pauses at all.
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Sent from my Pixel 4 XL using Tapatalk