T4.1 Ethernet Library

Probably my problem is of a typical "beginner"-type, but I just have no idea what's going wrong. (already posted this in the hardware-thread)

I've got this MagJack module connected to the teensy 4.1. Of course I checked the soldering and cable connections.
But I can't get any of the examples given on "https://github.com/vjmuzik/NativeEthernet" working.
The busy LED is flashing, but it seems there is no communication at all.

Hope someone has any idea to solve this. Maybe the hw is broken somehow.
I am having problems converting an old code that worked with Teensy 3.2 and separate Ethernet module.

So far it seems to work mostly ok. DHCP works ok, but with Static IP it seems to hang if it is not connected to network where that IP is valid. Because of this I can not change the configuration via USB as normal.