@Ste_Nix14 is correct, only the Huawei hub supports guest networks.
I am not employed by TalkTalk, I'm just a customer. If my post has fixed the issue, please set Accept as Solution from the 3 dot menu.
TalkTalk support and Community Stars - Who are they?
I am 99% sure this Hub doesn't support Guest networks and that only the Huawei variation of these hubs do.
Could you please confirm @KeithFrench ?