No one will be able to give you a general answer. It depends entirely on the quality of the concrete wall, e.g. whether there are steel beams inside. These can extremely weaken the WLAN signals. Based purely on experience, I would have said to reckon with a maximum of 15 -25m. In the open (e.g. garden etc.) the reception is usually better. Under your circumstances, the range will depend on the concrete wall.