Issues with systems going offline can be cause by a number of issues. Some examples are, connecting an NVR to a switch instead of a router, general router issues, short DHCP lease times, out of date firmware, and ID issues in the P2P server.
That list is not exhaustive. If the device goes offline once, check to make sure the system is wired directly to your router with an ethernet cable, then check in the network settings to make sure DHCP is on, and the address shown there is internal (generally beginning with 192.168 or 10 or 172.16), and then reboot the system. If the issue happens again within a month, call support. I definitely do not recommend rebooting the system every 2 days until the end of time.
The phone based support can help figure out the cause for the issue directly so you won't have to fight with what is likely a simple fix.
We are available from Monday-Friday, 8am-7pm CST, and can be reached at 217-903-5037.