Android 4.3 - No internet access, unable to connect to the proxy server error
If you have cleared your Google Service Framework data to receive the update, it will change your device ID that Google uses to recognise your device. This also affects the tokens used by some apps (i.e. Google Now, Google Search, Chrome) and they won't connect to the Google servers properly and refuse to work for a while (this was like 24~48 hours for me, before these apps started behaving as the tokens were eventually refreshed). Other non-Google apps will continue working.

More details of why this happens can be found in this reddit post by a Google engineer:
https://www.androidpolice.com/2013/11/20/google-engineer-dan-morrill-sheds-some-light-on-the-nexus-ota-process-urges-you-to-never-clear-google-service-framework-data/