What happens when you google "what is my IP"? Do you get an IPv4 address such as x.x.x.x (x ranging from 0 to 255) or an IPv6 address such as x:x:x:x:x:x:x:x (x ranging from 0000 to FFFF)?

Because in the LN block explorer your unknown IP address is shown in the IPv6 format. Maybe your router is set up to support IPv6 by default and the lightning node client (or the acinq block explorer) is not able to properly handle it?