docker network "already exists / overlaps": Subnet Collision Fix

Symptom

compose up fails with "Pool overlaps with other one on this address space".

Two compose projects (or another Docker network) claim the same RFC1918 subnet.

1. List existing networks and their subnetsdocker network ls && docker network inspect <net> | grep Subnet

2. Prune orphaned networksdocker network prune -f

3. Pin a unique subnet per projectnetworks: { default: { ipam: { config: [{ subnet: 172.28.0.0/16 }] } } }

Assign each stack its own subnet range in compose.

Spinning up a fresh box to reproduce or escape this error?

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Last reviewed 2026-10-02 · NinjaOps SEO grid · DevOps blog