Like most things having to do with Wi-Fi, fixing these problems requires a certain amount of patience. Generally speaking Wi-Fi connections are finicky. If you lose your Wi-Fi connection from the LEAF, or so it has a strong signal from the Wi-Fi SSID of choice, and do a number of steps.
First, The Wi-Fi connections menu and tell it to forget the SSIDs that you want to reconnect..
Second, from the same menu shut the Wi-Fi off completely.
Third, power the vehicle down and let it sit for 5 minutes say.
Fourth, can go and cycle the power on the repeater or the router that's providing the Wi-Fi signal to the LEAF. Involves other pushing the on/off button or unplugging it and leaving the router or repeater off or at least 30 seconds. Unplug it back in, and stick around until it indicates that it's in connection with the master router in the case of the repeater or with the internet in the case of the router. Test the repeater or the router with a cell phone to make sure that it can be connected and it does have internet.
Fifth, go back to the LEAF, turn on, and turn on the Wi-Fi. After you do that you should see the SSIDs that you are interested in connecting to. By pressing the circle I button confirm their signals are strong.
Sixth, each SSID in turn and reconnected as if you were connecting for the first time including putting the password in. Once it connects make sure to depress auto connect on the display. You probably only want to specify one SSID as an auto connect. The circuitry if there's more than one will get into a race and you'll end up with the LEAF never connecting to any of them.
Seventh, You're all set. If you're not you have a choice of doing the sequence all over again. Still doesn't work then you might want to take it to the dealers to get the TCM module or something changed.
Again I emphasize most of this has nothing to do with Nissan or the Nissan LEAF. It's just that that router's these days are really complicated and the protocols aren't necessarily standard. Finally cheap routers and repeaters really push the margins of how the hardware is supposed to perform. Save money on manufacturing. It means that the set of devices with which they can communicate is smaller than otherwise. Really makes much sense to buy a cheap router repeater.