@Atticuu
If the LED is red on the C80, that means it disconnected from the ISP modem, be sure that you get a stable connection by connecting a computer directly to the ISP modem bypassing the router with the same Ethernet cable first, then check again if there is still a WAN IP address on the router web page when the internet disconnects.
BTW, who is your ISP? If there is still a WAN IP address on the router when it disconnects from the internet, you can try to change the DNS server on the router to something like 8.8.8.8 and 8.8.4.4 ((go to Advanced > Network > Internet), then reboot it again.