WiFi is poor in the house despite a repeater, what to do?

And one very important thing, try to find and set a channel that is not mercilessly overloaded. In our construction area, there are channels in the 2.4GHz band where there are sometimes 10 WLANs on them.

I'm just going to misuse the thread now:

I have 2 Ubiquiti Access Point Lite and only sparse reception in the entrance area + garden part. Now I have ordered a 3rd Access Point Lite.
Now I would like to visualize the reception quality with the map function.
I have uploaded my floor plan. According to various tutorials, I am supposed to trace the walls. However, the necessary button is missing for me.
Can someone tell me what the reason is?

Cannot check it myself, but for example, you can find the following suggested solution if you use the search engine of your choice:

For that Option, you need to select Designer Option when creating a map. I believe you can Edit an existing one, but it removes any existing devices that are already placed on the map.

Which Telekom router is it? The smart3 can also do mesh. Get that one if it is rented. Then connect the speedhome wifi as an access point directly to the LAN cable and everything will be fine!

We have the Speedport Smart. Can it do something like that too? It is rented.

And a very important thing, try to find and set a channel that is not mercilessly overloaded. In our construction area, there are channels in the 2.4GHz band where sometimes 10 WLANs are on them.

How can you check this and how, if necessary, change it, i.e., choose another channel?

How can you check that and how to possibly change it, i.e. choose a different channel?

There are various apps for checking. I think the Ubiquiti controller software offers that, I even believe it assigns channels automatically for the access points. On a Mac, there is "Wireless Diagnostics," which also allows you to check the channel allocation in the environment. However, you can always set it manually in the router/access point.