Hi @Girifir, welcome to KPN and also to our community!

When installing your modem to the fibre cable, you have a few options. First, installing your modem in the meter cupboard, but then you will indeed need a power socket. The other option is to use an internet cable (at least ethernet cat5), to install the modem elsewhere. It doesn't matter if this cable is 2 or 10 meters long, because you won't be losing any signal strength or speed. We don't recommend using the 4 pin telephone socket you mentioned, because these are telephone connections, with a different type of cable. 

You can also call with our customer service at the free telephone number 0800-0402 (or 06-1200 1200) if you need any help with placing and installing your modem. If needed, they can schedule an appointment with a mechanic to help you with this.

Thank you for the answer! I installed a power outlet in the meter cupboard and use powerline to get connection to my living room.

Good to hear @Girifir! Powerline is an option for sure, but for the best quality you'd best use an ethernet cable. So if your internet speed isn't the best, I'd advise you to look into that.

You could try to replace the old telephone cable between the utility board and your living room by an ethernet cable....

The two empty pipes at the top of the cupboard should run to the house. An ethernet cable could be made through this. That’s the best option I think. 

if there's some movement in the cable (try that by opening the phone contact and check if the cable moves when someone pulls at it and another one checks in the utility board), you could connect the new cable to the old and pull it through that tube, you only need to fix 2 RJ45 connectors at both sides