Contivity 100 VPN

I am having trouble with a Nortel VPN box, a Contivity 100. After putting the unit online, I lose contact with it in less than a days time, and it needs to be reset. It acts as though it drops out due to inactivity. The box was configured by an outside solution provider, but it resides on my network. Does anyone have any experience with this device, or noticed similar behavior with a Nortel device?