Connection to RB2011 constantly drops

Hi,
Trying to find out why winbox constantly is disconnected to our RB2011 regardless of wired or wireless connection to the RB2011UiAS-2HnD

Firmware is at 6.36.
winbox-disconnect.jpg
The popup shows up after 4 or 5 minutes sometimes even 2-3 minutes. This behavior also occurs when connecting to another remote CCR Mikrotik
Any idea as to why the above keeps happening?

Thanks.