@Discy - Thanks for the detailed answer and layout. I see you're Dutch; part of my family is, still have relatives there. Hup Holland Hup!!
So total area is ~2000 square feet (1200 house, 800 garden), or 185 square meters (105 house, 80 garden). Should be simple enough to cover.
Wiring is possible, which is great. And understood on silent/fanless gear - shouldn't be a problem.
Users/devices/traffic/bandwidth should be completely serviceable.
The 100/10 internet speed is fine, provided you run
SQM on the router to prevent
bufferbloat.
Understood on all the rest.
So for starters, a primer on gear. Consumer stuff will often be the most "all-in-one" and turnkey. It will usually have more bleeding-edge (but unproven) wifi features, while forgoing a fair amount of wired throughput horsepower and quality control on hardware and software. Small-business/whitebox gear will often be a half or full generation behind on wifi standards but usually more reliable, while offering way more throughput and reliability for routing and switching. Couple that with community software and firewall OSes, and you generally hit the sweet spot for a "next level" network at a reasonable price. Per
@coxhaus's addition, enterprise gear takes all of the above to the utmost levels of uptime, features and performance, and but even if purchased used or refurbished, rarely makes sense outside of special circumstances.
For your use-case, you may be able to get away with a single consumer all-in-one router, perhaps placed centrally on the main or first floor, but the primary challenge will be firmware/wireless stability and wifi client throughput at the broadcast edges. Stability can often be solved with third-party firmware, like
Merlin on Asus (AX88U), or, my preference,
OpenWRT on a certain Qualcomm hardware (Netgear R7800 for example). Wifi coverage could be solved by something like multiple Asus AiMesh-compatible routers, or via a turnkey, whole-house mesh product like Deco, Velop or Orbi -- all of which I recommend interconnecting by
wire first, wireless only if absolutely necessary -- but the only one I tend to recommend, Eero Pro tri-band, isn't available in Europe as far as I know (right?...frustrating).
That said, consumer stuff can start to become a balance of compromises. The remedy to much of that can be found via an approach using discrete components, SMB-quality or better. It's ultimately how the highest-performing networks are built anyways, and presuming the setup is done properly, will almost always produce a better result from the sum of the parts. Plus you gain very nice things that the consumer stuff lacks, namely VLAN support out-of-the-box, PoE-powered wireless APs and (usually) more seamless wifi roaming. One ecosystem that makes this method
very approachable is
Ubiquiti UniFi; the controller can be used to configure gateway, switches and access points all from a single dashboard, although for you I would run a different gateway, like pfSense -- much more throughput for your dollar plus point-and-click access to all the functionality you're looking for (VPN, SQM QoS, security, etc.).
For specific gear choices, a decent starting point might be a Netgate SG-3100 or APU-based pfSense appliance, plus UniFi for switching and wireless -- a CloudKey Gen2 controller, US-8-150W PoE switch, and two or three NanoHD (ceiling mount) or FlexHD (desktop mount) access points, all hard-wired (and powered by PoE) to the switch, and placed equidistant/staggered for optimal coverage and overlap. Not a trivial cost (probably $1000 to $1200 USD total), but you didn't specify a hard budget and I just wanted to throw something out there that would definitely be
rock-solid, set-and-forget.
The suggestions above can certainly be tweaked or substituted per your budget or otherwise (sub in TP-Link Omada for UniFi, for example) but I hope the overview helps to paint a picture of things look out for and how to address them.