Did the upgrade itself fail, or does the internet connection fail after the upgrade?
I had a similar problem , where the 4.3.21 from where I started had a stable connection, it totally failed after the upgrade to 4.7.2
After deleting the known networks setup, and selecting another SSID it worked.
So far the problem was that the SSID I used was using the 5 GHz DFS channels (all above the 36,40,44,48 is DFS in Europe) . 4.3.21 will connect to those, 4.7.2 does not.
Later there was unstability seen. The wifi signal was very unstable on both radio's. Setting them to LOW was the best, but still very unstable setting. No fix so far.