Bt router

[Dave142]

I've just had bt fibre broadband installed but the router will only work if the old power supply is plugged in, the openreach installer  said  that it doesn't the old supply 

[licquorice]

Don't understand the question, can you clarify what you mean please.

[chrisjp]

Are you on fibre to the cabinet (FTTC) with a copper line to your house and a BT mastersocket, and then an RJ11 cable connected to your router to provide your broadband connection?
Or are you on fibre to the premises (FTTP) with an Optical Network Termination (ONT) unit which is then connected to your router via an RJ45 ethernet cable?
If the latter is the case, when you talk about your router are you in fact talking about the ONT?