I'll answer a bit aside your question.

If you've got 40 users, including servers, why do you stay with home edition ? It's not the target of this edition. You should go for a real hardware UTM.

Sophos is tight-lipped about the specs of their UTM/XG devices.

Look here....what CPU do these have, how much RAM do they have? 

https://www.firewalls.com/products/firewalls/sophos/xg/comparison

OK, I found the technical brief. http://dttstores.com/media/documents/sophos-xg.pdf

"Another point is that often the hardware version for the OS is really optimized for this h/w, so with a standard PC you do not have same result."

that's probably an important aspect. But the licensing prevents me from using anything else than the home edition. Therefore, my goal would be to find the most powerful hardware for the home edition while taking the limitations into consideration.

P.S. on the webpage of QOTOM I can't find the I7 version. Have they reduced their portfolio?

The link I provided states it has a Intel® Core™ i7-5500U Processor 4M Cache, up to 3GHz.

https://www.aliexpress.com/item/Industrial-PC-Gateway-Firewall-Router-for-pfSense-Core-I7-5500U-AES-NI-4-Gigabit-NICs-QOTOM/32855356778.html

There's also a different model where you can choose your CPU.

https://www.aliexpress.com/item/QOTOM-4-LAN-Mini-PC-with-Core-i3-4005U-i5-5250U-processor-and-4-Gigabit-NIC/32812678037.html?spm=2114.search0103.3.59.3b9462d5hPor2W&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10130_10068_10324_10342_10547_10325_10343_10546_10340_10548_10341_10545_10696_10084_10083_10618_10307_10313_10059_10534_100031_10103_10624_10623_443_10622_10621_10620_10810_10811,searchweb201603_25,ppcSwitch_5&algo_expid=d34c88dd-7706-4a90-b6de-f7c03df5156d-8&algo_pvid=d34c88dd-7706-4a90-b6de-f7c03df5156d&priceBeautifyAB=0

I was going to use a Qotom i5 for my home lab but ended up getting three defective units in a row. Their quality control is not what you might call "on point" and the CMOS battery on all of my units was attached to the motherboard using a dongle that flapped around inside the case without being attached to anything. The specs on these machines are really good for the price, but be warned that you are opening yourself to a bit of risk.

For reference, I finally gave up and went with this guy -> https://www.amazon.com/gp/product/B072ZTCNLK/ref=oh_aui_detailpage_o01_s00

I found the build quality to be much, much better. I threw my own drive and RAM in and ended up with a device that specs out somewhere between the 125 and 135 for a whopping $350.

-Gary

Amazon also sells the XG 115w base appliance for around $635. It only has 4Gb of ram but it's optimized for the XG firmware it might be OK. Performance wise I don't know how it would compare.

https://www.amazon.com/Sophos-XA1B1CSUS-XG-115w-TotalProtect/dp/B019G2UKFW?th=1

They also make a 6 port version available with up-to an i5 if you want more power.

https://protectli.com/6-port/

-GP

the QOTOM-Q375G4 with I7-5500U seems to be the most powerful from the given links. Since the main difference between i5 and i7 is hyperthreading, maybe even i5 i sufficient.

with 8gb of RAM and 128 SSD (is this enough?)

Since the Wifi Option is almost for free, does it make sense to get it in terms of compatibility with Sophos XG?

this comes down to 430$ plus tax and custom fees.

Furthermore, has anyone tested this Unit with Sophos XG?

6 ports are nice, since you could seperate networks without vlans, I guess. 

but this one starts at 599 without ram and sdd. In this price range the supermicro e300-d8 could also be an option.

On the one (of three) Qotom units I had that worked (for an hour) I had to disable USB3 in the BIOS to get the USB installer to boot. During load, the installer could not find the mSATA drive, but that may have just been due to my unit being defective. I swapped out the mSATA for regular SATA (a nice feature of these micro machines) but could not get the unit to boot again so was unable to test further.

ok, that doesn't sound promising.

In this case both the i5 and i7 are dual core with hyper threading. The main difference is the base frequency. The i7 has a MUCH higher base frequency of 2.4GHz instead of 1.6GHz. And the i7 will top out at 3GHz instead of 2.6GHz.

Also the built in wifi is not compatible with Sophos XG. So get the no-wifi option. 8Gb of RAM and 128Gb SSD should be more than enough. In fact a 64Gb SSD should be fine as long as you don't keep logs saved for too long.

I am running UTM 9.5 with a 128Gb SSD and 8Gb of RAM and it is more than plenty even with web filtering and intrusion prevention running. RAM never goes above 45% and that's with a total of 6.8 Gb RAM available due to graphics memory set aside. So this should give you an idea.

In this case both the i5 and i7 are dual core with hyper threading. The main difference is the base frequency. The i7 has a MUCH higher base frequency of 2.4GHz instead of 1.6GHz. And the i7 will top out at 3GHz instead of 2.6GHz.

Also the built in wifi is not compatible with Sophos XG. So get the no-wifi option. 8Gb of RAM and 128Gb SSD should be more than enough. In fact a 64Gb SSD should be fine as long as you don't keep logs saved for too long.

I am running UTM 9.5 with a 128Gb SSD and 8Gb of RAM and it is more than plenty even with web filtering and intrusion prevention running. RAM never goes above 45% and that's with a total of 6.8 Gb RAM available due to graphics memory set aside. So this should give you an idea.