I've done a TON of work in this for reasons and can tell you that streaming over 2.4Ghz especially is an anti-pattern unless you're dealing with super low-quality streams and/or only dealing with 1-2 devices. Even 5Ghz can get froggy with traffic contention. Working against a 15fps 1080p stream on 5Ghz is actually how I test streams with poor health and unpredictable behavior. Throw streaming over TCP into the mix and oof.
Also throwing another network component into the mix may not work for most folks.
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PS: Before someone yells at me for saying "TCP streaming" because "clearly UDP is the right tool for the job!": nope. TCP is the use-case.
You can, and it solves one of the problems: other clients wanting to use your bandwidth. With careful setup, and a low noise floor (ie not an apartment block) you could do this.
However you have to remember that you can only really run as fast as your slowest wifi camera[1]. That means that in practical terms, you need to make sure that all your cameras are syncing at the highest practical speed (this means not using the on board antenna in most cases)
[1] its more complex than this, but my understanding is that slower devices eat up the available transmit/receive time. which means that everything else is slowed down.
However a word of warning:
Wifi streaming video can really degrade your wifi for other devices. especially if the streaming device is at the edge of the range of the wifi.
Ethernet streaming is really the way forward.