MacBook Air wifi conncection problem after sleep

I have an early 2014 11" MacBook Air, 1.7 GHz, 8GB memory, running OSX 10.11.3. I am having a problem after computer sleeps. Upon wake-up, everything seems fine, but there is a problem reconnecting to wifi. Sometimes turning wifi on, then off, solves the problem. Most of the time, I need to re-boot to restore proper wifi connection. Re-booting always fixes the problem, so I know it a problem with software, not wifi or router. The problem may have started since I installed the latest OSX update about a week ago. Any suggestions?