Error starting user land proxy: listen tcp4 127.0.0.1:2375: bind: address already in use

I run docker-socket-proxy alongside Homepage but somehow the proxy refuses to start because the bind address is already in use.

Error response from daemon: driver failed programming external connectivity on endpoint dockerproxy (0412ec4ffda68af87f84323b217a6b9b5d02f3dee5a14c41bb2fb882918e55e8): failed to bind port 127.0.0.1:2375/tcp: Error starting userland proxy: listen tcp4 127.0.0.1:2375: bind: address already in use

The docker compose code is:

  dockerproxy:
    image: ghcr.io/tecnativa/docker-socket-proxy:latest
    container_name: dockerproxy
    environment:
      - CONTAINERS=1 # Allow access to viewing containers
      - SERVICES=1 # Allow access to viewing services (necessary when using Docker Swarm)
      - TASKS=1 # Allow access to viewing tasks (necessary when using Docker Swarm)
      - POST=0 # Disallow any POST operations (effectively read-only)
    ports:
      - 127.0.0.1:2375:2375
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    restart: unless-stopped

The netstat output shows no process bound to that address:

tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:8008            0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -
tcp        0      0 0.0.0.0:8443            0.0.0.0:*               LISTEN      -
tcp        0      0 127.0.0.1:34491         0.0.0.0:*               LISTEN      383633/code-33fc5a9
tcp        0      0 172.18.0.1:49956        172.18.0.9:9696         ESTABLISHED -
tcp        0      0 10.0.0.6:9696           172.18.0.7:35190        ESTABLISHED -
tcp        0      0 10.0.0.6:8989           172.18.0.12:36456       ESTABLISHED -
tcp        0      0 10.0.0.6:8008           172.18.0.2:37090        TIME_WAIT   -
tcp        0      0 127.0.0.1:34491         127.0.0.1:54342         ESTABLISHED 383633/code-33fc5a9
tcp        0      0 127.0.0.1:54342         127.0.0.1:34491         ESTABLISHED -
tcp        0      0 10.0.0.6:37092          10.100.0.2:445          ESTABLISHED -
tcp        0      0 10.0.0.6:7878           172.18.0.12:57696       ESTABLISHED -
tcp        0      0 10.0.0.6:9696           172.18.0.7:35208        ESTABLISHED -
tcp        0      0 10.0.0.6:22             10.10.2.156:50823       ESTABLISHED -
tcp        0      0 172.18.0.1:49946        172.18.0.9:9696         ESTABLISHED -
tcp        0      0 172.18.0.1:49944        172.18.0.9:9696         ESTABLISHED -
tcp        0      0 10.0.0.6:9696           172.18.0.7:35198        ESTABLISHED -
tcp        0      0 10.0.0.6:9696           172.18.0.7:35220        ESTABLISHED -
tcp        0      0 172.18.0.1:41260        172.18.0.7:8989         ESTABLISHED -
tcp        0      0 172.18.0.1:49966        172.18.0.9:9696         ESTABLISHED -
tcp        0   3212 10.0.0.6:22             10.10.2.156:49950       ESTABLISHED -
tcp        0      0 172.18.0.1:49932        172.18.0.9:9696         ESTABLISHED -
tcp        0      0 10.0.0.6:8008           172.18.0.2:37088        TIME_WAIT   -
tcp        0      0 10.0.0.6:9696           172.18.0.7:35178        ESTABLISHED -
tcp        0      0 172.18.0.1:39962        172.18.0.2:7878         ESTABLISHED -
udp        0      0 0.0.0.0:111             0.0.0.0:*                           -
udp        0      0 0.0.0.0:7359            0.0.0.0:*

What could cause this? Also, I'm not sure to which network I should bind the container. I tried both a separate network and the same network as Homepage.

Start with the docker-compose service definition, especially its ports and network settings, and compare the published host port with Docker’s view of active bindings. Reproduce the startup failure using the supplied configuration and inspect the proxy/container logs; done means the cause is identified and the correct binding or network setup is documented.