Your new phone should have come with an otg adapter. Its a little thing, like a USB stick, except it has a male usb c on one end, and a female usb port on the other. The usb c goes into the new phone and use the usb port to connect to ur old phone using its charging cable.
Maybe because you have an A series it may not have come with one, i know the S and Note do. If not they are literally a couple of quid and u can buy them anywhere online.
You don't necessarily need the adapter btw, if both phones were usb c for example and u have a usb c to c cable, then it'll connect without the adapter.
Oh i should mention, that when it uses WiFi, it doesn't mean its using your actual network, like your home WiFi. Its using WiFi Direct to connect one device directly to the old one, so you could do this in the middle of a desert, the connection is phone to phone (like Bluetooth, but faster). So if your home WiFi is unreliable, don't worry about it, it doesn't use it.