After a long time of doubting what would be best for me (partly with a distance of +/- 40 meters that I had to bridge), I asked Coolblue for advice.
Dennis (from Coolblue) has really provided me with fantastic advice, not a quick reply but really specific questions about the situation and offered various solutions, thank you for that.
Ultimately, I mainly went for convenience and the possibility to easily expand the network, so the TP-Link Deco M5.
In my case it has become the 4-pack, 3 in the house and 1 for the garden house. It is striking that you will receive a 3 pack and a single pack.
Prepare/Connect:
From my provider I received a modem/router of which I had the router function turned off (this can be done by calling customer service and asking if the modem can be put in "bridge mode" (possibly. WiFi spots from your provider expires with this)) .
Now the modem only transmits the wired signal and the Deco will take care of the router functions. You can also set the Deco so that you do not use its router function (Accesspoint mode), but it is recommended to let the Deco function as a router.
Then you need to install the Deco app for your Android or Apple device, unfortunately other systems are not supported and a web interface is also missing, although it is planned to be released soon.
In the Deco app you need to create a TP-Link account, so you can't let the Deco work without such an account, so keep that in mind.
The app now guides you through the entire setup process where you really only have to enter a name what you want to call your network and a password and the network is ready to use. No really, it's that simple!
My experience is that immediately after the first (main) Deco you can also register the other Deco's, you can then unplug them from the power and put them in a different location, they will then automatically make contact again.
By first registering all Deco's, you can easily update all Deco's in one go so that you don't have to update them individually. You will automatically receive a message about this in the app.
Recognition of the Decos in the system is done wirelessly and you must be within range of another Deco to do this, once they have been assigned you can place them wired out of range of the other Decos.
The Deco's can therefore communicate wirelessly with each other (so you only need power), however, this system can also communicate wired with each other through the 2 LAN ports on each Deco, wired is always preferred but not necessary!
The mutual communication of these types of devices is called "Backhaul" (if you come across that term somewhere).
App/Settings/Functions:
The Deco app has a nice organized appearance, but it sometimes takes a while to find where you can change the settings, the homepage gives an overview of the currently connected devices, a button under which you can see whether all Deco's are working properly, a button for antivirus and for parental controls.
Although it can hardly be found anywhere on the internet, it turns out that the antivirus from Trend micro that is installed on the Deco's, which is certainly not a replacement for the antivirus program on your PC, has a free license duration of 3 years, after that it will most likely be a payment service.
In the parental control you can create profiles and filter certain content, set online time and bedtime, useful if you have children.
It comes with a messaging service that notifies you as soon as a new device is connected to the network and when there are updates.
A little further in the app, under the menu button, more functions are hidden, you can test the internet speed, this concerns the speed that you get from your provider and not the speed with which you are connected wirelessly at that moment.
There is a blacklist where you can exclude devices, an update button, a WPS button that I don't think can be used in combination. the M5 works, a possibility to assign multiple network administrators and a Qos option.
By means of the Qos you can set which traffic in the network should have priority, for example you can indicate that gaming has more priority than downloading.
Then 2 relevant buttons remain, Wifi and Advanced, in the wifi menu you can see the name of your network and your password, by shaking your phone or tablet you can share this via e.g. Whatsapp, you can also switch your guest network on and off here.
For the more technical people among us, the main network gets an IP range of 192.168.0.xxx and the guest network 192.168.2.xxx, you can't change this.
You can use the guest network nicely for all your guests, so they can't reach e.g. your NAS connected to your regular network.
I have noticed that the guest network currently only broadcasts from the main Deco in the meter box and not via the other Deco's, I have sent an email to TP-Link about this but unfortunately have not received an answer so far.
In the advanced section you will find settings for IPv4 and IPv6, the operating mode (Router or access point), port forwarding, VLAN, fast roaming, tp-link ddns, notifications and monthly reports.
Two settings worth mentioning here are that you can switch off the LEDs on the Deco's between certain times, useful if there is one in the bedroom and the Address reservations, with this you can assign all your devices a fixed IP address, first put you fix the ip and after that you can change it in any range (100-199).
Operation/conclusion:
The three Deco's in my house provide perfect coverage (50s house with wooden floors). After placing the Deco in the garden house, I also have perfect coverage throughout the garden. And for the time being, apart from the guest network that is only accessible from the main Deco, I have had no problems at all.
You can't hang the Deco's by the way, I solved this in the meter cupboard by screwing three screws against the edge of the Deco in the wood (just do it by hand).
The app and firmware are constantly updated so that new functions become available and there seems to be a web interface.
The range of a single Deco is not extremely large, however, because they connect to each other, this is not a problem.
The price, which is usually described as expensive, is also not that bad, a router with 2 or 3 access points often costs more. and with this you are also rid of all wifi problems, at least that is what I have experienced so far.
All in all a great system that you can set up without any knowledge, highly recommended. Perhaps not extremely many setting options, but all standard options are there and this will be more than sufficient for 98% of the users!