We have an issue with two E400's we've installed at a site. We use them to provide a free wifi service and have it set up using the internal click through splash page. Mobile phones, both apple and android, have no issue being redirected to the splash page then passed through with internet access. But when tried with a laptop the only way to get onto the splash page is manually typing in the IP of the AP into the URL. Is there anything I need to do on the AP that I have missed for a laptop to automatically redirect me to the spash page when trying to access say www.Google.co.uk? Have tried both Windows 7 and Windows 10 Laptops.
As you have mentioned the phones are working fine which means your DNS server is working fine on your network. On laptops if you type any IP address then it should be getting redirected and if you type any domain or URL then that also should get redirected. If URL redirection is not working then can you check if your DNS server details are valid on the laptop and as a test run you can disable guest access and see you are able to access all domains from your laptop. Once it's ensured your network is fine for you laptop then enable guest access and check things out. If possible take a wireshark packet capture on your laptop and send across to us.
You can do ipconfig/all for checking the DNS details and default gateway on your laptop and disable guest access on the WLAN and check ping to google.co.uk. If it's working then enable guest-access and try redirection by typing this google.co.uk on the browser and accept the exception for the certificate if any and if nothing loads on the browser then type any IP address on the browser then it should get redirected, it need not be AP IP. If it's getting redirected only on AP IP address then most likely your laptop is not able to reach your network default gateway.