ZMODO?

I recently purchased and installed a 8ch ZMODO system. I continue to have problems viewing it from my cell phone. I can view from the computer monitor I have connected. It seems like it constantly times out when I try to remotely log in via my cell phone app. I will have to reboot the router and once rebooted, it will work. But again, won't last and will prevent me from from logging in remotely, until I reboot the router again. Not sure if it matters but I have a ASUS router. I also check and make sure the IP address hasn't changed. Any ideas? Greatly appreciate any help I can get. Very frustrating to say the least. Thank you.