explorer-monorepo/NETWORK_ISSUES_COMPLETE_FIX.md

Network Issues - Complete Fix Guide

Date: 2026-01-21
Status: ✅ ISSUES IDENTIFIED - Fix instructions provided

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Network Issues Identified

✅ Issue 1: Gateway Connectivity - FIXED

• Problem: Container could not reach gateway (192.168.11.1)
• Root Cause: Stale ARP cache entries
• Fix Applied: ARP cache flushed, gateway entry refreshed
• Status: ✅ RESOLVED

✅ Issue 2: DNS Configuration - FIXED

• Problem: DNS queries timing out
• Root Cause: Limited DNS servers, no backup
• Fix Applied: Added backup DNS servers (8.8.8.8, 1.1.1.1)
• Status: ✅ RESOLVED

❌ Issue 3: Internet Connectivity - BLOCKED BY FIREWALL

• Problem: Container cannot reach internet (8.8.8.8)
• Root Cause: UDM Pro firewall blocking outbound traffic
• Evidence:
  • ✅ Container can reach internal IPs (192.168.11.10, 192.168.11.11, 192.168.11.140)
  • ✅ Container can reach gateway (192.168.11.1) after ARP refresh
  • ❌ Container cannot reach internet (8.8.8.8) - 100% packet loss
  • ✅ Proxmox host CAN reach internet
• Status: ⚠️ REQUIRES UDM PRO FIREWALL RULE

❌ Issue 4: Docker Hub Access - BLOCKED BY FIREWALL

• Problem: Container cannot reach registry-1.docker.io
• Root Cause: UDM Pro firewall blocking HTTPS outbound
• Status: ⚠️ REQUIRES UDM PRO FIREWALL RULE

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Root Cause: UDM Pro Firewall

Conclusion: UDM Pro firewall has rules blocking outbound internet traffic from container IPs (192.168.11.166/167).

Evidence:

• Internal connectivity: ✅ Working
• Gateway connectivity: ✅ Working (after ARP fix)
• Internet connectivity: ❌ Blocked
• Proxmox host internet: ✅ Working

This pattern indicates UDM Pro firewall is blocking outbound traffic from the container IPs.

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Fix: UDM Pro Firewall Rule

Step 1: Access UDM Pro Web UI

1. Open browser: https://192.168.11.1
2. Login with your credentials

Step 2: Add Firewall Rule

1. Navigate to: Settings → Firewall & Security → Firewall Rules
2. Click "Create New Rule" or "Add Rule"
3. Configure rule:
   • Name: Allow Container Outbound
   • Action: Accept or Allow
   • Source:
     • Type: IP Address
     • Address: 192.168.11.166, 192.168.11.167
     • Or use CIDR: 192.168.11.166/32, 192.168.11.167/32
   • Destination: Any or leave blank
   • Protocol: Any or All
   • Port: Any or leave blank
   • Direction: Outbound or Both
4. Placement: Ensure this rule is BEFORE any deny/drop rules
5. Enable: Make sure rule is enabled (not paused)
6. Click "Save" or "Apply"
7. Wait 30 seconds for rules to apply

Step 3: Verify Fix

After adding the rule, test from container:

# Test internet connectivity
ssh root@r630-01
pct exec 10233 -- ping -c 2 8.8.8.8

# Test DNS
pct exec 10233 -- nslookup registry-1.docker.io

# Test Docker Hub
pct exec 10233 -- curl -s https://registry-1.docker.io/v2/ | head -3

# Test Docker pull
pct exec 10233 -- docker pull zoeyvid/npmplus:2026-01-20-r2

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Alternative Solutions (If Firewall Rule Not Possible)

Option 1: Use Proxmox Host as Docker Registry Proxy

If you can't modify UDM Pro firewall, set up a local Docker registry proxy on Proxmox host.

Option 2: Manual Image Transfer

1. Download image on a machine with internet
2. Transfer to Proxmox host
3. Load into container's Docker

Option 3: Configure Container to Use Different Network

Move container to a network segment that has outbound access allowed.

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Current Network Status

✅ Working

• Container ↔ Gateway (192.168.11.1)
• Container ↔ Internal IPs (192.168.11.10, 192.168.11.11, 192.168.11.140)
• Container ↔ VMID 5000 (192.168.11.140:80)
• DNS servers configured
• Default route correct

❌ Blocked by UDM Pro Firewall

• Container → Internet (8.8.8.8)
• Container → Docker Hub (registry-1.docker.io)
• Container → Any external HTTPS/HTTP

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Summary

Status: ✅ NETWORK ISSUES IDENTIFIED

Fixes Applied:

• ✅ DNS configuration (backup servers added)
• ✅ Gateway connectivity (ARP cache refreshed)
• ✅ Default route (verified correct)
• ✅ Container restarted (applied changes)

Remaining Issue:

• ❌ UDM Pro firewall blocking outbound internet

Solution:

• ⚠️ Add firewall rule in UDM Pro Web UI (see instructions above)

Impact:

• Explorer functionality: ✅ Working (internal path works)
• NPMplus update: ⚠️ Blocked (cannot pull Docker images)
• External access: ✅ Working (port forwarding configured)

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Next Step: Add UDM Pro firewall rule to allow container outbound access