Problem IP when download files!

Hi.
I note that at a distance of time, the problem is still present. Particularly when downloading files … with all available clients. I have 2 networks … LAN and WIFI. When I am in the LAN, the ip that generates me for the download of the files is always that of the WIFI … and this cannot be changed. In fact during the configuration it is necessary to decide which IP to choose. And this is very frustrating. Can this problem be solved?