Try connecting with Ethernet to the modem/router and see if you can connect to the internet then. If this is the first time trying to connect to this wifi node with that laptop it might be that the laptop's antenna is not the same as what the router is broadcasting(could be n only from router and that laptop is older than your other 2 devices) could switch the routers broadcast to support your laptop if that's the issue. Could be that the router has the max amount of ip's it can give at that time so your laptop might be waiting for one to disconnect so it can take its place. If router has mac address restrictions set it could be stopping you.