Update: I ordered a new cable. In the meantime I saw that the modem came with a short cat5e cable in the box, plugged it in and sure enough - 1000Mb. Thank you for the help!
I recently got Gigabit fiber. It is connected to a Zyxel VMG8825-T50 modem. Through Wi-Fi I get roughly 200Mb on my laptop. Surprisingly, through Ethernet (using a cat5e cable, exact model: Cablexpert MOD8716309, brand new, 15m) I get only around ~95Mb. Checking on my router's homepage, I get...