Any official recomended source to download ad upgrade or downgrade current firmware? Waiting for tech support may take a lot of time, also they recommend HW change.

@terziyski Yes provided by ISP. After contacting tech support they have reported that the same issue have been occured on several other devices. Support assumes this is due to automatic FW update...

Network Incident Report: Rogue DHCP Server Loop Issue Summary The network is experiencing an infinite DHCP loop that drops client connections exactly every 2.5 minutes. A rogue DHCP server/interface...