Since I have had my Er605 I have noticed that when the power went out (the er605 has a battery UPS) the er605 would restart (not always. Every 15 or 20 times it would restart only once) and I thought it could be the quality of the ups that caused this restart but later I realized that when I disconnected and reconnected the line of my Isp 1 (Wan) it also restarted (It does not always happen. Every 15 or 20 times it restarts only once). I really don't understand what the fault could be. My topology in summary:

wan: ISP 1 connection 100Mb (Arris Cm820) Wan/lan1: ISP 2 connection 1Gb (onu)

Wan/lan2: Lan-Vlan2 (Switch)

Lan3: Lan-Vlan250 (Switch)

Lan4: Lan-Vlan100 (Switch) 

(Be careful, this has always happened to me with all the versions that have been released and in the configuration there is no scheduled restart ) 

Sorry if there are any translation errors