WiFi connected but not working after a while, unless i turn it off and on again (macosx sierra) I have a MacBook Pro (13-inch, Mid 2012) MacOsX Sierra 10.12.3 (16D32) and I have a weird issue with my office's WLAN: I can connect to WiFi, and navigate on internet, then (usually after around one minute) it stops working: I'm still connected (the top-right icon shows the wifi interface it's still on and connected to the network), but pages don't load anymore and request end up in timeout errors. If I turn WiFi off and on again everything works again for a while then it stops and I have to turn wifi off/on again. So the loop takes place.

I can't figure out what the problem is and isolate it, everything seems ok. I guess this is likely a network (router) problem, since it only happens at work, but my colleagues apparently don't have this problem. Plus, if it were a routing problem, why does everything works again after a simple wifi interface reconnection laptop side i.e. without doing anything router-side? 

EDIT:
I've done some test and it turns out after apparently loosing connectivity to internet it's still possible to ping public hosts. So, I guess, network is up,  DNS work correctly, and the problem should be limited to http data forwarding on port 80 (so, likely a routing problem)
Go to Network in System Preferences. Go to Advanced, and check the DNS Servers. You should have 8.8.8.8 and 8.8.4.4, add those if they are not on there. Now check if your ipv4 is set to DHCP, and turn off ipv6 if it is on.