2.5G LAN slow from Windows, normal from linux.

[me777]

I changed my Hardware to a N100 with 4* 2.5G i226-V ports.
Installed the current opnsense version and did some tests, the important ones are:
-internet is only 500M instead of 1G on the windows 11 PC.
-iperf3 sows 400-500M from the windows to the opnsense firewall.
-iperf3 shows full bandwith from Windows (5G NIC) to a debian server on the same 10G switch as the Router.
-iperf3 shows full 2.5G from the server to the firewall.

The next thing I did was restore the pfsense that was preinstalled on the box, the internet shows my 1G again.(I used the same ports)

I guess its just some setting I have to change, but both searching in this forum and google did not help yet.

Thanks a lot.