This happened to me as well on my Lumia 820 (Developer Device) with Portico update. Before the Portico update, WiFi kept on when I used IE to browse. But then WiFi would always disconnect on screen lock.
Now on Portico, I have enabled WiFi always on which works pretty good for notifications at least.
What I think, in Portico update, it should work like as following:
- When WiFi is set to always on, keep it on when not in battery saver mode
- When battery is low, battery saver mode turns on, and it should turn off WiFi when display is off as well, but connect WiFi after 30 minutes intervals for notifications and updates
- Now when user turns on the display in battery saver mode, it should connect to WiFi, and let user do the browsing or other internet activity on WiFi. When screen goes off again, it should turn off WiFi
- After phone is charges back again, the usual WiFi always on gets back.
I think its a bug, and I have already sent it from "send feedback" option on my phone to Nokia. Hopefully they will look into it and ask MS to fix it in next update.
// chall3ng3r //