With the router that you try, you will firstly have to enter your username and password provided by Talktalk into the connection settings. I’ve found an article on Talktalks own page of what extra settings you will require https://community.talktalk.co.uk/t5/Broadband-Security/Setting-up-a-Non-TalkTalk-Router/ta-p/1324129
Any issues, send a reply, I talk you through.
BTW, Talktalk are pretty rubbish. My folks had them for too long and said it would crawl in the evening. Basically, they have too high a ratio of people to the line. I think it’s 50:1, which is why they are cheaper than everyone else. What it basically means, in the evening when everyone comes online, there is too much traffic.