A powerline adapter is an alternative to running in-wall Ethernet cables or relying on possible unstable WiFi.
Most home theater components are not in the same room as ahome data pipe’s router.
The powerline adapter is plugged into a wall electrical outlet.

Powerline network adapter plugged into a wall socket.olm26250 / Getty Images
It is connected to your router using an Ethernet cable.
Look for adapters that are rated faster than 300 Mb/s.
A basic powerline adapter model is large and box-like and can block your outlets where you plug it in.

Lifewire / Tim Liedtke
Also, see to it they’re close to your router and home entertainment system.
You could also consider upgrading your hardware if they’re old or outdated.
Many adapters have a pinhole reset button.
Using a pin or bent paperclip, press the reset button for about 10 seconds.
The equipment should then reset.