Major issues with SXK30 & VLANs

I bought a SXK30 a couple weeks ago. I have been experiencing frequent network down problems. The router lost internet connection and stopped all wifi connections. This could happen twice a DAY. Sometimes, the router reboot itself and everything went back to normal after a few minutes. But sometimes the router just stop responding at all. I need to reset it manually. I have not touch the VLAN part. I leave everything as default. I have tried to reset it, stopped the UPNP stuff, changed the NTP default server. And to no avail. So the problem came from the router itself or maybe the firmware its running (which I have updated to the latest one). This maybe the cheapest PRO model, but it should at least WORK as a normal WIFI router should be. I am TOTALLY disappointed. My solution is to return it and bought another brand. Sorry about it.