Need advice on USB wifi dongle for Linux...

[taisingera]

I have a Realtek 8191su usb adapter and it works fine in windows but in linux it connects and then after a few minutes, the speed slows way down. It doesn't disconnect, but according to SpeedTest.net, my download speed drops to <1Mbps. Right after I am testing on my Android phone on wifi and the speed is fine.

Any suggestions on a usb wifi adapter for linux that doesn't slow down? BTW, I am running Ubuntu MATE 16.04.1 fully updated. I have tried the trick to disable IPv6. I am just looking for a 802.11N adapter (nothing fancy).