In reply to a post by Plugy:

Thanks for the update trying to avid cables if possible. Running a speed test via app on firestick plugged in tv. I get a reading of 77dBm which l believe is a measure of the signal strength, this being in poor bracket?

If the WiFi signal isn't penetrating the walls and Powerline adapters aren't possible then wired Ethernet is your best bet.

A mesh WiFi system can be decent for extending range under the right circumstances but from reading your post you would need as many as 3 new devices to do this properly.
A new router that supports mesh WiFi (Talktalk's don't), 1 in your desired location, and 1 somewhere centrally in-between the 2.
Even then it just may not penetrate the thick walls.

My recommendation is a wired run of cat5e/cat6 to a WAP situated in your extension.

Whatever you do don't buy anything labelled cat7/cat8.

Edited by j0hn83 (Sat 13-Mar-21 16:57:07)