unexplained slow download speed

Hi Mikrotik power users

I have a question regarding the download speed observed on my MikroTik hEX PoE model RB960PGS.

My modem (Ubee UBC1318 in bridge mode) outputs 1000/70 Mbps (down/up) as measured directly at te modems port 1.
However, when connected to the router, I only get 95/70 Mbps. I use a cat6 cable between the modem and the router.

Being an absolute novice, I have no idea where to start looking for explanations. Any suggestions?

Regards
Remco from the Cultuurhoek (in NL)