FIRST, you are not addressing Apple, as this is a user to user forum. So your "Dear APPLE" is wasted energy and breath.
SECOND, it can still be your router, even if 1,000 other devices connect flawlessly. Your router may have taken a "dislike" to your iPad. (Or more correctly, its DHCP server may have crashed, so it can't assign new IP addresses. Devices that already have IP addresses are unaffected, but a device requesting a new IP address can't get one.) Have you tried rebooting the router by removing all power from it for 30 seconds?
THIRD, the problem, if it is not the router, is in your iPad, not in any specific version of iOS. If the problem was with 6.1.3 I would have it on my 2 iPhones and my iPad, and the 2 dozen other iDevices in my office. None of them have any WiFi problems.
If you want the problem resolved you will have to do some diagnosis, or take it to an Apple store for help.