Mine has settled down now and I am following slavishly the instruction on screen to close the browser window after applying any changes.
I think this makes a difference. It does not like you watching the counter count down to zero. That's my theory so far anyway.
Prior to this I was watching the counter all the way down to zero and when switching the WLAN on or off for instance, the light would not come on or go off and no connection to internet was re-established. Then I had trouble getting into the web interface.
Fingers crossed, this is what was causing my problems. Let me know if it works for you - that is, if you haven't already been doing so.
Don't know where to get firmware but if you find out let us know - just in case
eXtended on wireless range is better though.