If your IP address only changes every 6 months you can probably just use the IP address. When not at home I enter the IP address of my router followed by :350. Each router is different but for mine I set the external port to 350 and asked the router to forward that port to port 80 on my DVR IP address. You then need to pick a somewhat random port to use externally and setup your router to forward that port to your DVR. For mine the default DVR port is 80 which you should leave as is. You'll also going to need to forward a port to the DVR so the router knows which device you want to connect to. You need to use the IP address of your router. However that IP address isn't visible outside your network.
On my home network I go to 192.168.1.76 (the 192.168 part is likely similar to the first 2 numbers you use). I just set up a similar DVR last weekend. The IP address you use at home is different than the IP address you'd use outside.