If your WiFi network uses the ‘faster’ 5GHz band (instead or as well as the 2.4GHz band) the effect of walls and distance is far greater. It is generally advised to only use the 5GHz band within the same room as the router, as it may not work effectively through walls.
Change your device settings to prevent automatic connection to the 5G network if you are likely to roam around your house when using it. In general we recommend that devices with a fixed position, in the same room as the router e.g. TVs, streaming devices, audio equipment etc use the 5G network if available and any mobile devices such as phones, tablets, laptops etc are restricted to the 2.4GHz network.
Please bear in mind that both the 2.4GHz and 5GHz connections operate at greater speeds than the bandwidth capacity of your connection, while 5GHz is promoted as faster than 2.4GHz in reality there is often no discernible difference when using.