Laptop holding onto old ethernet ID

Hi, new to this so excuse if wrong area, my wife has a laptop she uses for her cycle training room, no idea what spec but I think a fairly new HP.  We used to have a TP-Link ethernet link plug setup for her to use the home internet running from a power port in the front room.  This was identified as TP-Link 814.  We have now upgraded to the BT home network using a disc in her room which take the router id BT8914G6.  All good but, yesterday she brought the laptop down to use in the front room, and plugged the ethernet cable in as she is not sure of wifi speed, and I noticed that it was identifying our BT router as TP-Link 814.  After she did her route planning I did some checking and the laptop will not forget the old TP-Link id even tough it is no longer used, is not switched on, we gave it away, I went back upstairs and it s the same. 

I did all the error checking and it cannot see the BT router as anything other than TP-Link.

How do I get her laptop to solve the memory issue?  many thanks 

In what menus/dialog boxes do you see the words TP-Link 814 ? Can you post a screenshot or two?

I'm guessing this could be something as simple as just clearing the ARP cache. If not, it might be a registry setting somewhere which could be changed/deleted, as long as it isn't critical.
 

Edited by Shplad, 19 April 2024 - 04:10 PM.

What do you mean by "disc in her room"?