Today I reinstalled pfsense, because of squid wasn't uninstalled correctly.
I hade no configuration done at all, so a reinstall seemed the fastest way to go.
So, reinstalled with exactly the same configuration.
pfsense says 1000Mbit on WAN and 1000Mbit on LAN, but I can only measure 100Mbit.
Without the pfsense-router it goes up to 200 where it's supose to be.