DE0-Nano-Soc with Kernel 4.1.17-ltsi: only Gigabit working

I use a custom Kernel based on the 4.1.17-ltsi. The board works fine when connected via gigabit Ethernet.
As my later application needs to use 100 MBit only I switched down to 100MBit by setting the link speed in my managed switch 100MBit full duplex via its web GUI.

As soon as I do so the DE0 board loses the link and doesn’t negotiate the new link speed.

I read that it may have to do with the “EMAC Splitter” which from my understanding is a piece of IP to be included in the design when using the FPGA fabric for some custom Ethernet on the FPGA side.

As on the DE0 the Ethernet PHY is hooked up to the HPS part, I have no idea if I need to implement additional logic to support 10/100 MBit or if this splitter is part of the silicon and as such always present.

Mailinglist Entry
descibes the symptoms even though using a custom board.

Is the DE0 Nano capable of running 10/100/1000Mbit or is there additional provisions on the hardware side to be made?
Can someone guide me into the proper direction?

Thanks in advance