I have a Samsung Tablet 4 10.1 SM-T530 with Android 5.0.2, and earlier this week, the Wifi acted up.
It does connect to Wifi-networks (I've tested several), but it doesn't seem to be connected to the internet. I've tested different browsers and apps, but they just can't access the net. Chrome gives me the error "DNS_PROBE_FINISHED_NO_INTERNET".
I've tried restarting, reconnecting, resetting to factory, updating firmware via PC, running Wifi-fixer, changing the date and time (syncing with router), changing from DHCP to static IP, and restarting the router, but to no effect.