Do you need LAN cables in the garage?

So we shouldn’t do without the CAT socket in the garage?

I personally wouldn’t do without it. Who knows what it might be useful for in the future.

Do wallboxes have to be connected to LAN?

No, they don’t have to. For example, we have a Zappi from myenergi. Here the connection is established using a wireless hub, which is then located directly in the utility room (of course, it also depends on the distance between the garage and the utility room).
But there are certainly boxes that have a LAN connection. It depends on what kind of box you want.

For 500 euros I would definitely give it up, if there is power there it will also handle a wifi repeater in the future Except if you want to put in a server farm for bitcoin mining later

I would have a maximum of 1 LAN cable installed in the garage.

In the garage, you can create more LAN ports with a switch if necessary.

Use cases for LAN in the garage:
- possibly wallbox
- running LAN cable to the garden/garden shed
- access point in or on the garage wall for the garden.

But the access point in the living room by the patio door should have enough power to adequately cover the garden?

We have a KFW55 house.

For 500 euros I would definitely skip it, if there is power there a wifi repeater will also manage it in the future
Unless you want to throw a server farm in there later for bitcoin mining

That also depends entirely on the house.
With a low budget option I would also forego it and try to find another solution or possibly do it myself.

With a higher standard, with a nice garage, I definitely wouldn’t do without LAN, unless it’s right next to the utility room and the problem can be solved quickly with a drill. ;)

In any case, lay a LAN cable into the garage. There are already many applications today (Photovoltaik Wechselrichter wurde noch nicht erwähnt) and there will be more.

Whether your access point is sufficient for the garden depends on the radiation direction and the size of the garden. I would actually want to make sure that the coverage is sufficient. So better lay a cable there as well.

Our garden is 11x20m in size

The photovoltaic inverter goes to the basement in the technical room

I would say that our house is low-mid budget.
Of course, I want to save as much as possible to invest the saved money from unnecessary things into other things.

If we should lay the cable into the garage and problems might otherwise arise, then we would do that as well