I can't explain it.
For some people the device works without problems, for others it doesn't.
What could be the reason for this? Has the design of some devices been changed, different chips used or something similar?
well you could have wifi interference which will screw the device up.
I have two set to medium speed they are pretty much flawless for me.
But I do lose the wifi connection every 2-3 weeks I need to reboot and I am back in 2-3 minutes.