Dear maintainer and community,

Steps to reproduce the issue

• Disabled ipv6 on your ubuntu.20.04 box via

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

• Disabled ipv6 on your docker daemon via "ipv6": false in /etc/docker/daemon.json
• Restart docker service or even reboot the host.
• Run a container like docker run -p 12345:80 --rm nginx:latest
• docker ps report port 12345 published for both ipv6 and ipv4

Expected behavior

• Docker should ONLY report an ipv4 published port.

How we catch this?
By investing a bug on AWS ECS:
On aws ecs we catch with docker-ce v20.10.6 The ipv4 and ipv6 being different after 14 days uptime on couple instances, all using 20.10.6

Another problem underneath: Different port number on ipv4 and ipv6
Here an extract on my ecs logs where you can find that the port on the ipv6 is not the same as ipv4

Ports="[{8080 50195 0.0.0.0 0} {8080 50191 :: 0}]"
Ports="[{8080 50195 0.0.0.0 0} {8080 50191 :: 0}]"
Ports="[{8080 50195 0.0.0.0 0} {8080 50191 :: 0}]"
Ports="[{8080 50195 0.0.0.0 0} {8080 50191 :: 0}]"
Ports="[{8080 50196 0.0.0.0 0} {8080 50192 :: 0}]"
Ports="[{8080 50196 0.0.0.0 0} {8080 50192 :: 0}]"
Ports="[{8080 50196 0.0.0.0 0} {8080 50192 :: 0}]"
Ports="[{8080 50196 0.0.0.0 0} {8080 50192 :: 0}]"
Ports="[{8080 50197 0.0.0.0 0} {8080 50193 :: 0}]"
Ports="[{8080 50197 0.0.0.0 0} {8080 50193 :: 0}]"
Ports="[{8080 50197 0.0.0.0 0} {8080 50193 :: 0}]"
Ports="[{8080 50197 0.0.0.0 0} {8080 50193 :: 0}]"
Ports="[{8080 50198 0.0.0.0 0} {8080 50194 :: 0}]"
Ports="[{8080 50198 0.0.0.0 0} {8080 50194 :: 0}]"

Solved by restarting dockerd: port on ipv4 and ipv6 are identical again