Home Appliance for Gigabit fibre connection 1000 mbps

Hello

I'm using an old HP Desktop with 2 NIC's and an Intel Quadcore Quad Core2 Q6600 @ 2.4GHz. This device is to slow for my home as I have a symmetrical Gigabit fibre connection.

Unfortunately I bought a Shuttle XPC slim XH110v with i7-6700, 8 GB ram and 120 GB m2.sata which is not compatible with Sophos home UTM9. With this PC and pfSense I get around 900 Mbps up and down.
http://www.shuttle.eu/de/produkte/slim/xh110v/

Now I’m asking for advice for a silent or low noise PC with lots of power. I would prefer a LGA1151 socket and I’m willing to spend some serious buck on it (500 to 700 US).

So what chipset / mainboard is supported by Sophos and give me real throughput? Goal is something between 500 and 900 Mbps. It would be helpful if the HW is available in Europe.