@terziyski I've updated the firmware without any problems and will see if this happens again, but since this issue was not happening very often in the first place let's consider this solved until...

@terziyski I haven't tried factory reset yet, and re-configuring from scratch would be a huge pain because I don't remember everything that I did, and have a lot settings especially DHCP reservations...

I bought this router about 2 years ago and since some time ago (unfortunately I'm not sure since when) the routers sometimes becomes un-operational - the Internet connection drops, the LAN...