Install a dual-band router (examples of Linksys models were given in
http:#25227838), and dual band adapters on as much as possible... with simultaneous dual-band the cameras could stay on 2.4GHz. Some are dual-band yet NOT simultaneous dual-band... i.e. they can run 2.4GHz *OR* 5GHz, so you have to read their descriptions and data sheets carefully.