I have a problem with connection on my TL-WPA4221KIT. The main powerline adapter is connected via ethernet to the router upstairs and I have three extenders throughout the house. I think everything is paired correctly (all 3 lights are on) because the two downstairs and the other (in a far room of the house) are all working excellently (full signal and fast internet). But when I try to use the internet wirelessly in the office upstairs (sitting right next to the main powerline adapter and the router) the connection is really slow. (I also have a main computer in the office that connects via ethernet and provides fast internet). I have a feeling that I'm still connecting to the extender downstairs. Could this be and how can I solve it? Apologies for my lack of technical knowhow or jargon. Please advise. Thank you.
Connecting to the adapter/extender AV600
Model: TL-WPA4220 KIT