404 Not Found for specific target after working previously - intermittent routing failure #608

New Issue

MrUnknownDE · 2026-04-05T17:26:31+02:00

MrUnknownDE commented

2026-04-05 17:26:31 +02:00

Originally created by @nkkfs on 11/21/2025

Describe the Bug

Hi, I'm experiencing an issue where one specific target (Nextcloud AIO) returns 404 Not Found through Pangolin, while all other targets on the same backend server continue to work correctly. Direct access to the backend works perfectly with the same headers that Pangolin should be forwarding.

Environment

Deployment: Docker on separate VM in Unraid
Backend: Nextcloud AIO on Unraid server

Target Configuration

Domain: nextcloud.example.com
Target URL: http://192.168.1.100:11000
SSL: Enabled
Custom Headers:
X-Forwarded-Proto: https
X-Forwarded-Host: nextcloud.example.com
Priority: 100
Health check: Shows as unhealthy

Other targets: Multiple other services on the same Unraid server (same IP, different ports) work correctly through Pangolin.

Issue Details

Accessing https://nextcloud.example.com through Pangolin returns 404 Not Found
Direct access to http://192.168.1.100:11000 works correctly
Other services proxied through Pangolin to the same backend server (192.168.1.100) work fine
Issue appeared spontaneously after working correctly for an extended period

Logs

Gerbil sometimes shows:
ERROR: 2025/11/21 15:33:00 Error reading UDP packet: read udp [::]:21820: use of closed network connection
INFO: 2025/11/21 15:33:21 Fetching remote config from http://pangolin:3001/api/v1/gerbil/get-config
ERROR: 2025/11/21 15:33:21 Error fetching remote config: Post "http://pangolin:3001/api/v1/gerbil/get-config": dial tcp 172.18.0.2:3001: connect: connection refused
ERROR: 2025/11/21 15:33:21 Failed to load configuration: Post "http://pangolin:3001/api/v1/gerbil/get-config": dial tcp 172.18.0.2:3001: connect: connection refused

Traefik sometimes shows:
2025-11-21T15:33:22Z ERR Provider error, retrying in 260.669806ms error="cannot fetch configuration data: do fetch request: Get "[http://pangolin:3001/api/v1/traefik-config\](http://pangolin:3001/api/v1/traefik-config%5C)": dial tcp 172.18.0.2:3001: connect: connection refused" providerName=http

Testing Performed

Direct backend test with same headers (successful):

curl -v -H "Host: nextcloud.example.com" \
     -H "X-Forwarded-Proto: https" \
     -H "X-Forwarded-Host: nextcloud.example.com" \
     http://192.168.1.100:11000

Result: HTTP/1.1 302 Found, redirects to https://nextcloud.example.com/login

Through Pangolin: Returns 404 Not Found

Other services on same backend: All work correctly

Container restarts: Restarted Pangolin, Gerbil, Traefik - no change

VM restart: Full VM restart - no change

Clean reinstall: Reinstalled Pangolin completely, but didn't help

Questions

Is there additional debug logging I can enable to see how Pangolin processes requests for this specific domain?
Could this be related to how Pangolin handles health checks? The health check shows as unhealthy, but other unhealthy targets still proxy requests correctly.
Are there any known issues with specific backend configurations (like Nextcloud AIO with its internal Caddy/Apache setup) that could cause Pangolin to return 404 despite the backend being accessible?

Additional Context

The backend (Nextcloud AIO) configuration hasn't changed. The issue affects only this one target while all other proxied services to the same backend continue working normally. This suggests something specific about how Pangolin routes this particular domain/target combination, but with no errors in logs, it's difficult to diagnose.

Environment

OS Type & Version: Fedora Server 43 (but Ubuntu 24.04LTS had same problem)
Pangolin Version: 1.12.2
Gerbil Version: 1.2.2
Traefik Version: 3.6.2
Newt Version: 1.6.0
Olm Version: NONE

To Reproduce

Just try to reverse-proxy Nextcloud AiO Apache container.

Expected Behavior

Access Nextcloud dashboard

*Originally created by @nkkfs on 11/21/2025* ### Describe the Bug Hi, I'm experiencing an issue where one specific target (Nextcloud AIO) returns 404 Not Found through Pangolin, while all other targets on the same backend server continue to work correctly. Direct access to the backend works perfectly with the same headers that Pangolin should be forwarding. ## Environment - Deployment: Docker on separate VM in Unraid - Backend: Nextcloud AIO on Unraid server ## Target Configuration - Domain: nextcloud.example.com - Target URL: http://192.168.1.100:11000 - SSL: Enabled - Custom Headers: X-Forwarded-Proto: https X-Forwarded-Host: nextcloud.example.com - Priority: 100 - Health check: Shows as unhealthy Other targets: Multiple other services on the same Unraid server (same IP, different ports) work correctly through Pangolin. ## Issue Details - Accessing https://nextcloud.example.com through Pangolin returns 404 Not Found - Direct access to http://192.168.1.100:11000 works correctly - Other services proxied through Pangolin to the same backend server (192.168.1.100) work fine - Issue appeared spontaneously after working correctly for an extended period ## Logs ``` Gerbil sometimes shows: ERROR: 2025/11/21 15:33:00 Error reading UDP packet: read udp [::]:21820: use of closed network connection INFO: 2025/11/21 15:33:21 Fetching remote config from http://pangolin:3001/api/v1/gerbil/get-config ERROR: 2025/11/21 15:33:21 Error fetching remote config: Post "http://pangolin:3001/api/v1/gerbil/get-config": dial tcp 172.18.0.2:3001: connect: connection refused ERROR: 2025/11/21 15:33:21 Failed to load configuration: Post "http://pangolin:3001/api/v1/gerbil/get-config": dial tcp 172.18.0.2:3001: connect: connection refused ``` Traefik sometimes shows: `2025-11-21T15:33:22Z ERR Provider error, retrying in 260.669806ms error="cannot fetch configuration data: do fetch request: Get "[http://pangolin:3001/api/v1/traefik-config\](http://pangolin:3001/api/v1/traefik-config%5C)": dial tcp 172.18.0.2:3001: connect: connection refused" providerName=http` ## Testing Performed **Direct backend test with same headers (successful):** ```bash curl -v -H "Host: nextcloud.example.com" \ -H "X-Forwarded-Proto: https" \ -H "X-Forwarded-Host: nextcloud.example.com" \ http://192.168.1.100:11000 ``` Result: `HTTP/1.1 302 Found`, redirects to `https://nextcloud.example.com/login` **Through Pangolin:** Returns 404 Not Found **Other services on same backend:** All work correctly **Container restarts:** Restarted Pangolin, Gerbil, Traefik - no change **VM restart:** Full VM restart - no change **Clean reinstall:** Reinstalled Pangolin completely, but didn't help ## Questions 1. Is there additional debug logging I can enable to see how Pangolin processes requests for this specific domain? 2. Could this be related to how Pangolin handles health checks? The health check shows as unhealthy, but other unhealthy targets still proxy requests correctly. 3. Are there any known issues with specific backend configurations (like Nextcloud AIO with its internal Caddy/Apache setup) that could cause Pangolin to return 404 despite the backend being accessible? ## Additional Context The backend (Nextcloud AIO) configuration hasn't changed. The issue affects only this one target while all other proxied services to the same backend continue working normally. This suggests something specific about how Pangolin routes this particular domain/target combination, but with no errors in logs, it's difficult to diagnose. ### Environment - OS Type & Version: Fedora Server 43 (but Ubuntu 24.04LTS had same problem) - Pangolin Version: 1.12.2 - Gerbil Version: 1.2.2 - Traefik Version: 3.6.2 - Newt Version: 1.6.0 - Olm Version: NONE ### To Reproduce Just try to reverse-proxy Nextcloud AiO Apache container. ### Expected Behavior Access Nextcloud dashboard

MrUnknownDE closed this issue

2026-04-05 17:26:31 +02:00

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Reference: github/pangolin#608