You have this set up wrong. Probably in your router.
See if there's a youtube video on setting up the static ip's correctly.
if you have a TWC/Spectrum "all in one" modem router combo, good luck...
may not be configurable... use a modem only wired to a router you own.. If the cameras are wifi, that's a total disaster.... wireless radio must be locked to a channel, not in auto/scan mode, dhcp lease set for a day not an hour, all cameras need static ip's, etc.
set dhcp start at 192.168.1.100 , put the camera server at 192.168.1.99 and camera's below that....
Set the 192.168.1.99 port up to have the proper : port numbers forwarded both tcp and dhp. I'd also avoid using port 80, change it to 380 or 480. the 3000 or 8000 3g port is usually ok
as long as you don't swap modems or routers, your TWC/spectrum public ip rarely changes.
you locally get at the camera server at 192.168.1.99:380 and out of the house at your public ip xxx.xxx.xxx.xxx:380 or xxx.xxx.xxx.xxx:3000 or 8000 for a 3g /4g phone.
If the public IP keeps changing, it sounds like NAT is off and the combo is in bridged mode and that a lan device called up the new public IP.
Combo's are horrid, unstable for advanced routing which is what you're doing. cable co's reset the router settings even in COAM units. It's possible you have wifi interference and that's resetting it as well, lock it to ch 3 or 8 turn off auto/scan modes.
turn off WPS
If you set up DHCP start for 192.168.1.100, the gateway will need to be set to 192.168.1.1 do not use 192.168.1.2 to.10 for anything.
Sel router to autodetect wan settings and also turn off IPv6.