New hub installed but upstairs Wi‑Fi keeps dropping in the back bedrooms

Hi all, had my Nexora broadband installed last week and the internet itself seems fine downstairs, but upstairs is a nightmare. The two back bedrooms keep going dead every evening, especially on Zoom calls. I’ve rebooted the hub a few times and moved it away from the TV as someone suggested, but it hasn’t changed much. I’ve got the standard Nexora Hub in the hallway and the house is a 3-bed semi, if that helps. Any ideas before I lose my mind?