Docker compose `resolving target address ... resource temporarily unavailable`

[MarcHagen]

Describe the Bug

Hi since, 1.4.0 i have troubles getting stable connections to the the newt instance.
My setup is a docker compose setup that has multiple services running, like Unifi controller.

I was pinned to 1.3.0, never had any issues. With 1.4.0+ there where stability issues around resolving.
Now I am on 1.8.0 and it is still an issue. It renders my whole site unreachable until i restart the container.
Pinning back to 1.3.0 and all seems to be working fine for more than a day.
1.4.0+ gives me issues after ~12 hours.

newt-1  | ERROR: 2025/12/23 19:52:46 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:46 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:46 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:46 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:47 Error resolving target address: lookup uisp-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup uisp-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup uisp-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error connecting to target: dial tcp: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error resolving target address: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable
newt-1  | ERROR: 2025/12/23 19:52:48 Error connecting to target: dial tcp: lookup unifi-controller on 127.0.0.11:53: dial udp 127.0.0.11:53: connect: resource temporarily unavailable

Environment

• OS Type & Version: Alpine Linux 3.21
• Pangolin Version: unrelated
• Gerbil Version: unrelated
• Traefik Version: unrelated
• Newt Version: 1.4.0, 1.4.1, 1.8.0
• Olm Version: (if applicable)

To Reproduce

Pangolin with at least one newt site.
Public resource (http or tcp/udp) with Targets Configuration to the newt instance with unifi-controller:443 as target.

Site:
Newt + (in my case) Unifi controller in the same docker compose shared network (aka same file).

NOTE:
It does NOT matter what service, ANY service in this compose stack will fail.
This is just an example, a simple Hello world will also fail.

---
name: site
include:
  - ./pangolin-tunnel/compose.yml
  - ./unifi-controller/compose.yml

networks:
  servicenet:

---
services:
  newt:
    image: "fosrl/newt:1.8.0-rc.0"
    restart: unless-stopped
    environment:
      - PANGOLIN_ENDPOINT=https://<endpoint>
      - NEWT_ID=<id>
      - NEWT_SECRET=<secret>
    deploy:
      resources:
        limits:
          memory: 4G
          cpus: 1
    logging:
      driver: json-file
      options:
        max-size: 200k
    networks:
      - servicenet

---
services:
  unifi-controller:
    <snip>
    networks:
      - unifi
      - servicenet
  unifi-mongo:
    <snip>
    networks:
      - unifi

networks:
  unifi:

Expected Behavior

Resolving internal services like normal.