W8960 V3 is very old and we cannot expect a newer firmware. You can try to load the old firmware back to see if the problem will disappear.

Your WA850RE is running in latest firmware? What's the firmware version of your TL-WR542G? Can you provide the screenshot of the problem you described?

What kinds of mobile device? Did you try to change some settings on web interface of WPA4220, like channel, security settings etc.?

Laptops connected to WPA281's Wi-Fi but no internet? What's the operating system of those laptops? Is there any IP address, default gateway etc. obtained on your laptops? If you fail to connect,...

Submit a new ticket or re-open 18101 here to complain such a problem and seek help. Good luck. http://ticket.tp-link.com/index.php?/Tickets/Submit

Did you contact support for Spanish Users? http://www.tp-link.com/en/Support/contact/?categoryid=530 For Spanish Users Local No.:+34 902 060365 E-mail: soporte.es@tp-link.com Service Time:From 9:00...