Smart tv apps tend to suck. Slow and buggy. I'd use a separate device. Then run hdmi direct from that to the tv and another line from the device to the receiver for audio. Though the best solution is a new receiver.
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Streaming Devices: Nvidia Shield, 2x Roku 3's, 1st/2nd gen chromecast, ATV4k, Apple TV 4, xbox 360/one
Displays: Vizio M602i-B3, LG OLED65B6, panasonic ax100u on a 145" S-I-L-V-E-R painted screen, 40" Samsung
Receivers: Denon X3300, Yamaha RX-V663. Bluray/UHD player: Oppo UDP-203