In the past couple of weeks, my Laptop and iPhone have not been able to connect wirelessly to the router. The wireless LAN shows up on the laptop, but I cannot connect to it. Also, the AP Discovery scan does not pick up any of the other WLANs in the neighbourhood.

Once I reboot the router, everythnig works fine again for between a few hours and a day.

It could be that another AP is using the same channel and is causing your WLAN to throw its toys out of the pram.

Try changing the channel the WLAN works on and see if that helps.

I have tried that already (but thank you for the suggestion). When I reboot, I check the AP scan and have never seen another AP on my channel.