I've got 2 Roku's (series 2 & 3), a PC, 3 Macbooks, an iMac, 2 network printers, 3 iPads, 3 iPhones, an Android phone, 2 DirecTV DVRs and an Apple TV all running on my home network along with my BrewPi (connected via WiFi) without the issues you're experiencing.
My home network is comprised...