I happened to come across an alternative fix for forcing docker to unclaim ports: https://stackoverflow.com/a/61239636/6868722
To quote:
This worked for me on Linux, and without having to delete any resources.
# Stop docker sudo service docker stop # Find your particular zombie proxy processes sudo netstat -pna | grep docker-proxy # tcp6 0 0 :::8025 :::* LISTEN <PID_A>/docker-proxy # tcp6 0 0 :::13306 :::* LISTEN <PID_B>/docker-proxy # ... # Kill them sudo kill -9 PID_A PID_B ... # restart sudo service docker start