I don't have experience with this box, but generically, this is what I would do:
- Alter DHCP range to give me plenty of room for static, so 192.168.1.50-255 say.
- Allocate static IPs in the 188.8.131.52-49 range to CCTV & servers etc.
- Check subnet, gateway etc. on static devices too.
- Open ports to static IPs.
- Enable ping from internet (probably the cause of your packet loss).
If you've manually configured the IP on a static device, and opened the port, it should work.
To troubleshoot you could connected a laptop in place of the device, allocating it the same static IP, and use/write an app on open up a port on that machine. Then try and connect through from the internet.
When opening ports, I'm assuming that you're mapping external port X through to IP Y, also on port X?