Good morning! When it comes to the New-Build developments and the setups, here's what we can advise you on.
We'd like to confirm something. Do you have a patch panel (with different sockets/ports) and ethernet (LAN) ports connected to it around the flat that could transmit the signal? If that is the case, you can plug the WAN/ethernet cable into the Hyperoptic socket and instead of plugging the other end into the router, you can plug it into one of the ports on the patch panel. Which port on the patch panel you'll choose will be up to you, depending on where the broadband signal from it would be transferred to. For example, Port 1 can be connected to the LAN port in the living room. To have a better signal you can relocate the router from the cupboard and then connect it to that living room port. This is just an example of how you could go about this.
Please note that we weren't the ones installing the internal wiring and that you may need to speak to your concierge/building management about the connection of the patch panel to the ports around the flat.
We hope this information helps. If you have more questions, feel free to send us a private message and we'll gladly advise further.
We wish you a pleasant rest of the day and stay safe!