UPD: When I`m using torrent without limit of bandwidth or making a videocall via Skype router is still rebooting. Uptime is less than 10-20 minutes...

It is powered with AC/DC adapter. Length of cable is approx. 1m.
I`ve just updated firmware to 2.39 and no reboots for now... Need to test more...

UPD: I`ve connected AC/DC adapter to UPS, but router still rebooting
UPD #2: uptime is more than 48 hours

I`ve got the same error. It happens once per 24 hours, but sometimes more frequently (one per hour). May be this is related to heavy load of router... Who knows...