The reason I think it's overheating is because I've seen "charging suspended, high temperature" many times on the LCD, but the device hasn't reset. Have you ever seen this message?
I have the same problem, with router type LTE2566-M634. Restarts / Reboots spontaneously and randomly and I don't know the cause. It doesn't matter if it's connected to a PC via USB or via Wi-Fi. I have the latest firmware "V1.00(ABTW.4)C0". I have two pieces of LTE2566-M634 router and they both behave the same, randomly…