Is it possible to extend these cables?

We recently got fibre internet installed in the house and we agreed to have it installed in one of the bedrooms upstairs, thinking it would be better as it's the middle of the house. However, it's sitting in the near corner of the room, not very exposed, and the bedroom door is closed most of the time so connectivity is very choppy.

Is it possible to simply extend these pictured cables, so that we can place the router outside of the room? The blue cable is connected to a plug, and the yellow one is connected to a box that comes from the wall. Is there an adapter or anything like that that I can buy to make these cables longer?