Skip to main content
Polar Cloud
Courses By User Type
All Topics

Troubleshooting Agent Connection Issues

  • By Polar Cloud Academy
  • Published: Nov 14, 2025
  • Rating
    Average rating: 0 No reviews

Outline

Symptom / Diagnosis:

The network is dropping the WebSocket connection every 60 seconds, which is preventing the agent from maintaining a stable connection to Polar Cloud.

What to check?

WebSocket Connection Timeout

Your firewall or network equipment is configured to close idle connections after 60 seconds. This needs to be increased to at least 5-10 minutes for WebSocket connections.

Where to check:

  • Firewall settings: Look for "TCP timeout", "idle timeout", or "session timeout"
  • Proxy server settings: WebSocket timeout or keep-alive settings
  • Router/Gateway: Connection tracking timeout

Specific settings to change:

  • Set WebSocket idle timeout to 300-600 seconds (5-10 minutes)
  • Or disable timeout for connections to *.polar3d.com or your Polar Cloud domain

2. Whitelist Polar Cloud WebSocket Traffic

Add these domains to your firewall/proxy allowlist with 'no timeout' or 'persistent connection' rules.

Domains to whitelist:

  • *.polar3d.com
  • Any specific Polar Cloud server domains you use
  • WebSocket protocol (wss://) specifically

Firewall rule example:

Source: Any
Destination: *.polar3d.com
Protocol: HTTPS/WSS (port 443)
Action: Allow
Session Timeout: Disabled or 600+ seconds

3. Disable SSL/TLS Inspection for Polar Cloud

If your network uses SSL inspection/deep packet inspection, it may be interfering with WebSocket connections. Add Polar Cloud domains to the SSL inspection bypass list.

Why: SSL inspection breaks WebSocket's persistent connection handshake.

4. Check for Proxy Server Interference

If you're using a proxy server (like Squid, Blue Coat, Zscaler, etc.), it needs to be configured to properly handle WebSocket connections.

Proxy settings needed:

  • Enable WebSocket support
  • Disable connection pooling for WebSocket connections
  • Increase proxy timeout to 600+ seconds
  • Add Polar Cloud to proxy bypass list (if possible)

5. Network Equipment to Check

Check these devices/systems:

Testing Steps:

  1. Test from a different network (home network, mobile hotspot): If it works here, it confirms it's your school/corporate network
  2. Temporarily disable firewall/proxy (if allowed): If it works, confirms firewall/proxy is the issue
  3. Check with IT department logs:  Look for connection drops at ~60-second intervals, check for WebSocket connection denials or timeouts
  4. Work with IT to implement whitelisting:  Provide them the Polar Cloud domain list, request WebSocket timeout increase to 600 seconds

Need to send an email to your IT department?

Subject: WebSocket Connection Timeout Issue - Need Firewall Configuration Update

Hi IT Team,

We're experiencing issues with our 3D printer management software (Polar Cloud Agent) that uses WebSocket connections to communicate with cloud servers. The connection is being dropped every 60 seconds, which is preventing normal operation.

Issue:

  • WebSocket connection to *.polar3d.com disconnects every ~60 seconds
  • Connection successfully reconnects in 3-4 seconds
  • Pattern repeats continuously, causing printer monitoring issues

Requested Fix:

  1. Increase WebSocket/idle connection timeout to 600 seconds (10 minutes) for connections to *.polar3d.com
  2. Whitelist *.polar3d.com for persistent WebSocket connections (port 443/HTTPS)
  3. Disable SSL inspection/deep packet inspection for *.polar3d.com (if applicable)

Technical Details:

  • Protocol: WebSocket over TLS (wss://)
  • Port: 443
  • Domains: *.polar3d.com and related Polar Cloud infrastructure
  • Current timeout: ~60 seconds (needs to be increased to 600+ seconds)

Test: The connection works fine on non-corporate networks (home/mobile), confirming this is a network policy issue.

Can you help adjust these firewall/proxy settings?

Thanks, [Name]

---

Running on a Server?

We're getting feedback that using the agent on a server might differ slightly from running it on a personal computer. Run this test from the server command line to check WebSocket connectivity.

# Test basic HTTPS connectivity
curl -I https://printer4.polar3d.com

# Test WebSocket upgrade (if wscat is available)
wscat -c wss://printer4.polar3d.com/socket.io/?transport=websocket

Other quick checks:

# Check DNS resolution
nslookup printer4.polar3d.com

# Check if port 443 is reachable
Test-NetConnection -ComputerName printer4.polar3d.com -Port 443

# Check system time
w32tm /query /status

If your websockets connection to the server are still being blocked, these are the possible causes:

  1. SSL Certificate issue - The server might have an untrusted root CA, or the Windows machine doesn't have the certificate chain
  2. DNS issue - our printer server at printer4.polar3d.com might resolve differently on your network
  3. IPv6 vs IPv4 - You might be resolving to IPv6 but only IPv4 is properly routed
  4. Proxy settings - Windows system proxy settings might be interfering (even if firewall allows)
  5. Time/date mismatch - SSL certificates fail validation if system time is wrong