So I have an E4200V2 with pre-Smart Wi-Fi firmware (possibly stock) that I had been successfully accessing via its IP. After upgrading to Ver.2.1.41 (Build 164606) firmware last night, I can no longer access the router via its IP, only via myrouter.local (which resolves to the correct IP).
Using myrouter.local (http://myrouter.local/ui/1.0.99.162351/dynamic/login.html), the local login page is displayed with the Smart Wi-Fi login option underneath. Entering the router password gets me in no problem. But if I attempt the use the router's IP address (http://192.168.xxx.xxx/ui/1.0.99.162351/dynamic/login.html), I get the Smart Wi-Fi login page with the local access option underneath. Clicking on the local access link allows me to enter the router password as normal. BUT, at this point, the login sequence hesitates (web page flash), and I'm dumped back at the Smart Wi-Fi login page again. I never actually get logged into the router. Obviously the correct IP and password are unchanged and correct - and the behavior is 100% repeatable.
Yeah, I know I can just use myrouter.local, but KB article 25805 says it should work. It always has worked. And well, I've only got a couple dozen network devices, so I've memorized their IP's.
BTW, the new UI really gets in the way of getting work done. Why couldn't the local bloatware be saved for the Smart Wi-Fi account users? Could have satisfied users both experienced and inexperienced simultaneously.