This building is about 28 meter wide (the blue building and the red building together, basically everything that can be fully seen in the picture).

Would one of the new Cap XL be able to cover this building? I want to install it exactly in the middle.

One unit, if you can find it, doubtfull.

Yes, my distributor has the model in stock. (Wrong)

Just checked: I overlooked "Delivery time 55 days"

So what would you recommend for this project?

This is mainly for guests to this wellness hotel.

@Binser, here are some questions to help you plan a solution:

What is your performance objective for per-client Wi-Fi throughput (measured in Mb/s)?

How many concurrent client do you want to plan for? (Number of concurrent associations? Number of concurrent active eyeballs?)

Do you have sufficient upstream bandwidth to support your Wi-Fi performance needs (concurrent eyeballs x per-client Mbps)?

Attentuation of interior walls and structure varies according to materials. Best way to know is to perform some measurements.

CAPs are not very expensive. Buy two and try them in different locations and perform some objective testing (preferably with multiple types of client devices. Ask your guests to help test). You may need more than two CAPs.

Don’t forget, that Wi-Fi associations are a two-way relationship and you need to measure signal strength and SNR independently for each direction.
Use numerical values… number of bars on the GUI does not tell you.

Do you know how much RF noise (this is also known as the noise floor) there is in your environment? A quieter environment will require fewer APs to get you to the same SNR. Larger SNR will improve association speed and throughput.

Good luck!

Thank you for your advice.

I don't think more than 10 people will connect at the same time.

Usage will be low bandwidth, no streaming, just email, messaging, and the occasional skype or similar call - usage mainly from mobile devices.

The building is in a very small village, single house dwellings, so not much noise.

So basically throughput is not an issue at all, reach is more important.

Furthermore, some (most) people here will want to be in a low emission environment, since this is a place were detox and alternative medicine is being practiced. In fact the owner requested to have the network switched off at night for zero emission during sleep. That's also the reason why I don't think mesh would be appropriate.

Since the XL Cap is not available, what cap would you suggest within those parameters? Maybe I could do with three or at the most four caps?

Hm, I don't recommend what you are self-recommending either.

3, maybe 4.
Since radiation seems to be of importance, best to go with 4 otherwise one or more caps might be transmitting at their max

And if speed is not an issue, maybe go with the cheaper cAP or cAPLite, there is maybe no need for AC-speeds ?
Besides, nowhere I know there is Cap AC (XL) to be found ... the normal caps can still be found if you want.
BUT ... caveat ... this last part is not a future proof suggestion.

Thank you, holvoetn.