I am not sure what you mean by playback device. I have a Samsung HD - Non-smart TV. It connects via HDMI from a Roku device. Roku is connected wirelessly.
Quite honestly, I have no idea how Tablo and Roku work together.
Tablo gets the OTA signal from what looks like a 75 Ohm cable. There is also an Ethernet connection, a USB to the HDD, and a power cord. The Roku simply has an HDMI to the TV and a power cord. Those two wires are attached to the IR gizmo for the remote control. I assume the wireless signal is somewhere within the gizmo.
I can understand when or why Roku programming sometimes buffers. Oddly enough Netflix rarely buffers. When it does I assume it is because of usage from everyone doing the same thing at the same time, it just exhausts Netflix. Not necessarily because of the wireless connection.
Someone suggested I take the hard drive off-line from the Tablo. I have not tried that yet. If the HDD is dying, that could cause the buffering I experience when replaying a program.
What I don’t understand is why watching Live TV via Tablo anything buffers? In my mind, the OTA signal just happens to pass through the Tablo. At that point Tablo serves simply as a channel guide. And the channel guide is driven by a wired connection.
The router is a Linksys model EA 7500 that I bought in 2017.