Hopping between networks

I live in a house with thick walls and poor Wi-Fi signal coverage, so I have installed two Wi-Fi points – one for the ground floor and one for upstairs. The problem is that the downstairs one is first in the list of networks and so my MacBook Pro always tries to connect to this one first. If I am upstairs and it wakes from sleep it connects to the very weak signal from downstairs, even if I was connected to the upstairs one before. Is there a way to force it to reconnect to the same network each time? M Fulger Network preferences has an option in the Advanced settings that requires administrator authorisation to change networks. This will stop OS X from hopping networks automatically and will require your password whenever you try to change manually. But I think there’s a much better solution. Instead of splitting the house into several separate networks, configure the upstairs access point so that it extends the range of your network. This will tell it to rebroadcast the signal from the downstairs access point. The house now appears to have a single network that reaches everywhere. To set this up on an Airport Express, hold the reset button down until the yellow light starts blinking (this resets it) then reconfigure it in Airport Utility but choose ‘Add to an existing network’.