Q: ios 8.3 wifi problems with wifi??

Thanks for sharing what worked for you yuuhyakuta.   These various wi-fi problems have plagued every iOS 8 update, and it's still happening under 8.4.1 !!  I say various because some people report loss of connection and other people can't connect at all.  I am still having a long-standing difficulty, as follows:  At home, I'm connected to my Verizon router's wi-fi, and everything's fine.   I take my phone with me on errands, and when I get back home, SOMETIMES my phone does not automatically reconnect to router's wi-fi.   It sees the network, but demands my password, which it then tells me is WRONG, but it's not, because my Mac and my old iPad can connect anytime with the password I give. I was overjoyed, like you, some weeks ago when I found a fix in this thread that worked for me.    (It had proved absolutely pointless to take my phone to the Apple Store's genius bar, because, there, everything seemed to work fine.)

But alas, the problem came back, and this time what had worked before no longer worked.   My overall experience is that there are MANY settings you can change, resets you can do, power off and ons, router settings, restores and rebuilds and updates, but there does not appear to be one single reliable fix for this condition.   Whenever this has come up for me, I know I'm in for some frustrating (hours) time trying different fixes before, suddenly the password is accepted and the wi-fi works again. Unless black magic is causing these problems, it is Apple software bugs that are necessitating all these resets.   I have never in years of working with Apple products seen a problem this severe, directly affecting the core capability of a device, that has persisted for so long unsolved.  I guess my point to you is that I'm glad you solved your immediate difficulty, but you may be in for more disappointment.