How to restart WiFi interface without rebooting (it drops connection)?

I boot into ubuntu and it connects to the Wifi network fine. After about 10-15min the DNS stop resolving any website and a couple of minutes later network-managers tells me that I'm disconnected and tries to reconnect constantly to my router and fails to do it. Upon Ubuntu restart everything works fine for the first 10-15min again. When I boot into Mac OS X everything is fine with the same connection!

How do I restart wifi interface? sudo ifdow wlan0 just tells me that wlan0 is not configured and wlan0 doesn't appear in /etc/network/interfaces either, which I find strange.... (unless network-manager is doing it behind my back).

I had the same problem with ubuntu 15.10 after running on a wired network and having my laptop suspended and resuming when not on a wired network anymore.

I found this blogpost very helpful: http://blog.ostermiller.org/resetting-wireless-networking-on-ubuntu-without-rebooting/

You need to find your driver:

sudo lshw -C network

Look for the wireless controller and in configuration look for driver. In my case:

*-network
   description: Network controller
   product: Wireless 8260
   configuration: driver=iwlwifi latency=0

All I had to do to fix is run

sudo modprobe -r iwlwifi && sudo modprobe iwlwifi

I would have a look at dmesg too, and, after loosing connection, at the last messages of dmesg:

dmesg | tail 

Maybe dropping and reloading your wifi-module helps:

sudo rmmod ipw2100
sudo modprobe ipw2100

for example, for the intel-chipset. I had random problem with this chispset, which went away, after setting the IRQ in the BIOS.

You could try to find your wi-fi controller with lspci:

lspci | grep Network

I had the same problem here (using Maverick, I think it's a known bug), and I fixed it with rmmod + modprobe trick as @user unknown answered. Here I'm using a Realtek RTL8191SEvA device, which driver is named r8192se_pci.