Because the issues with Mikrotik switches are well documented here, for just about a year.
I have one of the switches that shut down a group every few days.
http://forum.mikrotik.com/t/crs354-48p-4s-2q-traffic-problem-on-ports-1-to-8/139024/1
Mikrotik os my favorite routing platform…
But the wireless is S–t, and the switches are a joke.