Is the remote a replacement too or are you trying to pair the old remote?
If the old one, did you reset it first?
At what stage are you trying to pair the remote? During setup or after the box is setup?
It's usually easier to pair the remote during set up as the box automatically tries to pair via Bluetooth at that stage. If you haven't tried it, try resetting the box back to factory settings and pair then.
I assume you have been trying to pair using the instructions here. If not give them a try.
Hope this helps.
Please remember to mark Solved Posts with Best Answer. Doing so helps other customers and saves TalkTalk's Support Team time by only looking at unsolved topics. Thanks, Steve (a fellow customer).
