Check if there is a  pre-installed inline telephone line, and telephone outlet in the room you need it,
to exchange it with an ethernet cable.

Otherwise I should recommend to exchange pre-installed Ziggo cable with ethernet cable.  Keep the Ziggo cable in the closet, and if you move out again, there is always a possibility to exchange back.

Try to do that by a handy student (dependent which city you are living, there could be a student helping office, specially for such jobs), or otherwise a handy neighbour. To do the job by a technician from KPN, it could be more expensive by call-out costs and minimum time calculating.

I do not know if there’s a telephone outlet where I need it, that’s why I need someone to check. I know there is one outlet but it’s “occupied” by the Ziggo cable (the KPN technician saw it). It’s also on the opposite side of the room from where I would need it.    

There are 2 ‘blank’ (covered by a plastic cap) outlets where I would need the ethernet cable, but I don’t know if the ethernet cable can come through from there.

The cost is not an issue, I’m just checking to see if KPN can take care of it, rather than call a third party electrician.

That “could” be a possibility??   Just open to see what is behind.

I am not from KPN, so wait for a response for a KPN employee as for this subject to discuss the possibilities to get a KPN engineer to fix it and have an indication of the costs.

Is it kind of a new house? They usually have covers like this; 

9/10 times behind this plastic cover there is a black cable to the cupboard/electrical installation. Is that also the place where the kpn box is? 
 

In the next picture below are the black wires, if you also see these in your cupboard / place where the modem is and you have those white covers with the black wires behind it then a KPN technician can put in a Cat5e cable with a pretty RJ45 box so you won’t have that plastic cover. 
 

To get an KPN technician to your house you will be charged 60 euros for the visit and get 45 minutes. For the 2 cables you will probably be charged the same. If I’m the one KPN would send the invoice would be between 100 and 120 euros depending on the time it would take. 
 

I hope this is enough information. 

Thanks @Ik_Hussel ! 

Just in case, this is how it looks like in the cupboard (I think called meterkast here in NL?), there’s no black wires that I can see

https://i.imgur.com/QcbskFj.jpg

And this is how it looks like if I unscrew the cover from the blank outlets in the room:

https://i.imgur.com/vejZptl.jpg

I don’t know if this says anything, for me they might mean an ethernet cable can come through, or they can be the secret passage to Narnia :_D

Sometimes the free cables are on the floor, are there pipes in the cupboard with the blue cable on the floor? In my opinion it should be possible but I can't be 100% sure. Thank you for the foto's. 

And yes, it is called meterkast

In the “meterkast” I do see already a blue ethernet cable going into  LL  (at the right)

Although the color of the cable of the open outlet is more light blue.
I wonder if it is by the bright light shining to it, or really more light of its own color?

Can it be the same cable as in "meterkast"?

Also wondering the other two white cables, as you can not seen the end of it.

Hi Golvellius, welcome on our board. 

You can always order a payed engineer. The one main issue is that an engineer will not drill through walls because they can't risk hitting a cable or gas pipe. (@Ik_Hussel can you confirm this?) Is this something that needs to be done? 

Depends on the wall, we do get a hammer drill machine (klopboor) from KPN. But the risk needs to be acceptable and the owner/renter is responsible for damage. But I do think there are empty pipes in this house. (loze leidingen)

Thanks for clarifying. @Golvellius I think you can go ahead and order one of our engineers, or of course find an electrician of your own.