smom-dbis-138/frontend-dapp/TROUBLESHOOTING.md

Troubleshooting Connection Timeout - 192.168.11.211

Issue

Connection timeout when accessing http://192.168.11.211/

Server Status ✅

All server-side checks pass:

• ✅ VM (2101) is running
• ✅ Nginx is active and running
• ✅ Port 80 is listening on 0.0.0.0:80 (all interfaces)
• ✅ Server responds with HTTP 200 OK from localhost
• ✅ Files are deployed correctly
• ✅ Nginx configuration is valid

Root Cause Analysis

Since the server is working correctly, the issue is network connectivity between your location and the server.

Possible Causes

1. Network Segmentation

   • Your machine may not be on the 192.168.11.x network
   • Different VLAN/subnet
   • Router configuration blocking inter-subnet traffic

2. Proxmox Host Firewall

   • Proxmox may have firewall rules blocking VM access
   • Container firewall enabled

3. Router/Network Firewall

   • Firewall rules blocking access to VMs
   • VLAN isolation
   • Network ACLs

4. VM Firewall (Fixed)

   • ✅ Disabled VM-level firewall
   • ✅ Updated nginx config to use default_server

Solutions

Option 1: Verify Network Connectivity

# Check if you can ping the server
ping 192.168.11.211

# Check if you're on the same network
ip addr show | grep "192.168.11"

# Test from a machine on the same network
curl -I http://192.168.11.211/

Option 2: Access via Proxmox Host

If you're on the same network but can't access directly:

1. SSH to Proxmox host first:

   ssh root@192.168.11.10
   

2. Then access from there:

   curl -I http://192.168.11.211/
   

3. Or set up SSH tunnel:

   ssh -L 8080:192.168.11.211:80 root@192.168.11.10
   # Then access: http://localhost:8080/
   

Option 3: Configure Proxmox Firewall

Check Proxmox firewall rules:

ssh root@192.168.11.10 "iptables -L -n -v"
ssh root@192.168.11.10 "pve-firewall status"

If firewall is blocking, allow traffic:

# Allow HTTP to VM
ssh root@192.168.11.10 "iptables -I INPUT -p tcp --dport 80 -s 192.168.11.0/24 -j ACCEPT"

Option 4: Use NPMplus Proxy (Recommended)

Since you have NPMplus configured, use it instead:

1. Configure NPMplus proxy host (see NPMPLUS_CONFIGURATION.md):

   • Domain: cross-all.defi-oracle.io
   • Forward to: http://192.168.11.211:80
   • Enable SSL

2. Access via domain:

   https://cross-all.defi-oracle.io/
   

This is the recommended production approach anyway.

Option 5: Check Router/Network Configuration

If you're on a different subnet:

1. Check your IP:

   ip addr show
   

2. Check routing:

   ip route show
   route -n | grep 192.168.11
   

3. Check if router allows inter-subnet traffic

   • Review router firewall rules
   • Check VLAN configuration
   • Verify routing tables

Quick Fixes Applied

✅ Updated nginx config to use default_server:

listen 80 default_server;
listen [::]:80 default_server;

✅ Disabled VM firewall:

pct set 2101 --net0 name=eth0,bridge=vmbr0,firewall=0

✅ Removed default nginx site that might interfere

Verification

After applying fixes, verify:

# From the server itself
ssh root@192.168.11.10 "pct exec 2101 -- curl -I http://127.0.0.1/"

# From Proxmox host
ssh root@192.168.11.10 "curl -I http://192.168.11.211/"

# From your machine (if on same network)
curl -I http://192.168.11.211/

Network Diagram

Your Machine → Router/Firewall → Proxmox Host (192.168.11.10) → VM (192.168.11.211)
     ?               ?                    ✅                      ✅

Each ? is a potential point of failure.

Recommended Solution

Use NPMplus proxy (already configured):

1. Access via domain: https://cross-all.defi-oracle.io/
2. Let NPMplus handle SSL/TLS termination
3. NPMplus is on the correct network and can reach the VM

This is the production-ready approach and avoids direct VM IP access issues.

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Last Updated: 2025-01-22
Status: Server OK, Network connectivity issue