I notice that my ethernet interface connected to ISP’s router has two ip addresses, like this:
3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 30:5a:3a:47:07:72 brd ff:ff:ff:ff:ff:ff
inet 192.168.2.13/24 brd 192.168.2.255 scope global dynamic noprefixroute enp6s0
valid_lft 242739sec preferred_lft 242739sec
inet 192.168.2.18/24 brd 192.168.2.255 scope global secondary dynamic noprefixroute enp6s0
valid_lft 242748sec preferred_lft 210348sec
Only the 192.168.2.18 works for remote connections via port-forwarding. Why are there two IP addresses?