Hi @FCWOOD,welcome to our forum!
Have you also tried a different cable between the Fiber unit and your modem?

If that doesn't solve I could also take a look if everything is in order on our end. Could you update your profile and let me know?
 

Hi, thank you!

Yes, when i connected the modem directly to the fiber unit I used a different CAT6 cable (one that was supplied with the installation). 

Profile has been updated and if you could check it would be greatly appreciated. 

Thanks @FCWOOD! I took a look at the line and everything seems to be in order from this end. I opened a ticket with our technical people to take a deeper look. They'll contact you about this, keep in mind they'll call from a private or 088 number!

One last question I forgot to ask. Which speedtest are you trying?  The best results would be with a speedtest app for windows or android.
A couple of other options for tests would be fast.com or kpn.com/speedtest

I have been using both KPN’s speed test and speedtest.net, which have both been giving me the same results. Thanks for checking for me and opening the ticket! I’ll look out for the call

Hi @FCWOOD, Are you still experiencing this issue?

My colleagues write that they havent been able to reach you and that they sent you a text message with their direct number and access code.

Hi Thomas, 

Had one of your engineers around today, but the problem seems to be a bit complicated, so still no resolution. They seem to think there’s some software problem somewhere but they are going to call me again this afternoon to get someone else out to have a look. Thanks again for opening the ticket for me, i’ll let you know what the problem was once its found!

Hi @FCWOOD, thanks for the update! 
From what I can see they have closed the ticket, is that correct? The explanation you did get the right speeds with the modem in the meter cupboard but when you move the modem to the livingroom the speed drops considerably. The ticket states you're taking it up with the home owner to check/repair those cables. 

Hi Thomas, 

Its turned out to be not quite so simple. The cable in the wall is now delivering 950 Mbps no problem when connected to the modem in the cupboard, however if i move the modem back into the living room and connect it to the cable in the wall it drops back to 100 Mbps. So I’m not so sure what the issue is anymore. The modem is okay in the cupboard for now, but the wi-fi is not always great in parts of our apartment, so i may call back to request a new modem to try or something.

You can always give us a call about this  (on 0800-0402)

I can't imagine the actual location making a difference in cabled speed. Did they also try a different cable?
To improve the Wifi you can also run our online wifimanager. 

Seems to me that the ethernet connection in your living room is wired incorrectly or is wired with a lower rated ethernet cable causing to fall back to a lower speed of max 100mbit.

You can test this by connecting a laptop directly to the router with an highspeed ethernet cable on the port that is used to connect to your living room. If you see speeds higher then 100mbit you proved it must be te cable running to your living room, or the ethernet wall-socket is wired incorrectly. With an ethernet tester this could be proven also.