diff --git a/dev2/README.md b/dev2/README.md
index 5bf5652..9b90a95 100644
--- a/dev2/README.md
+++ b/dev2/README.md
@@ -160,9 +160,12 @@ small file per site, so parallel migrations never edit a shared file:
   "companion_commands": { "genrewatch-worker": "bun run worker" },
   "env_overrides": { "SITE_URL": "https://example.com" },
   "pg_service": "Postgres-iVtY", "max_body": "256m", "branch": "master",
-  "env_remove": ["TURSO_DATABASE_URL", "TURSO_AUTH_TOKEN"] }
+  "env_remove": ["TURSO_DATABASE_URL", "TURSO_AUTH_TOKEN"],
+  "subnet_octet": 178 }
 ```
 
+`subnet_octet` replaces the `<port-3200>` in the app network `10.200.<n>.0/24` when another stack already holds that /24 (c0ncerts.com: bittorrented.com was hand-built on its 10.200.78.0/24).
+
 ### Secrets in `env_overrides`
 
 `sites.d/` is committed and this repository is public, so a value that is a
diff --git a/dev2/dev2-site b/dev2/dev2-site
index f1eddbe..d2f89aa 100755
--- a/dev2/dev2-site
+++ b/dev2/dev2-site
@@ -685,7 +685,9 @@ def render_compose(s, st, app_port_inside, build_args=(), node_preset=()):
     # ran out at 34 networks on dev2, and widening them means restarting dockerd
     # under every container. 10.200.<port-3200>.0/24 is deterministic and allowlisted
     # on the data ports.
-    n = s["port"] - FIRST_PORT
+    # `subnet_octet` in sites.d moves a site off a /24 another stack already holds
+    # (bittorrented.com was hand-built on c0ncerts.com's 10.200.78.0/24).
+    n = s.get("subnet_octet", s["port"] - FIRST_PORT)
     y.append(f"networks:\n  default:\n    ipam:\n      config:\n        - subnet: 10.200.{n}.0/24")
     # Healthchecks chosen by `dev2-site healthchecks` survive a re-render.
     return health_compose("\n".join(y) + "\n", st.get("healthchecks") or {})
diff --git a/dev2/sites.d/c0ncerts.com.json b/dev2/sites.d/c0ncerts.com.json
new file mode 100644
index 0000000..5d6de50
--- /dev/null
+++ b/dev2/sites.d/c0ncerts.com.json
@@ -0,0 +1,16 @@
+{
+ "db": "supabase",
+ "proxies": [
+  {
+   "host": "supabase.c0ncerts.com",
+   "port": 8278,
+   "max_body": "512m"
+  }
+ ],
+ "env_overrides": {
+  "NEXT_PUBLIC_SUPABASE_URL": "https://supabase.c0ncerts.com",
+  "NEXT_PUBLIC_SUPABASE_ANON_KEY": "secret:NEXT_PUBLIC_SUPABASE_ANON_KEY",
+  "SUPABASE_SERVICE_ROLE_KEY": "secret:SUPABASE_SERVICE_ROLE_KEY"
+ },
+ "subnet_octet": 178
+}