@Kpatchery,

Powerline adapters are super finicky, and it may not even be a device with interference causing the slowdown.

I would first check to make sure that the plug that you are sending data to in the kitchen, is on the same circuit as your other adapters. A degradation such as this could be caused by the signal having to travel to the breaker, where the bandwidth is nuked due to noise filtering, and then back to the adapter in the kitchen.

It could even be something as simple as a bad connection on the outlet, a degraded run of wire, or power lines could be bundled together causing excessive interference.

Try changing the outlet you are using in the kitchen, or even try moving the device outside of the kitchen to see if the behavior follows the device.