Connection Error with Alcatel Router (SMX-RNS20)
Problem
Section titled “Problem”When the SMX-RNS20 is installed behind an Alcatel router (common in Turkish mobile/fixed networks), the device may fail to establish or maintain a stable P2P tunnel. Symptoms include:
- Device shows “Online” in the portal but SX-Client cannot connect
- Connection drops immediately after establishing
- High latency or very slow tunnel performance
- Relay fallback used instead of direct P2P path
Root cause: Some Alcatel routers implement an aggressive NAT/firewall that drops UDP hole-punching packets used by the Simplinx P2P protocol. When direct P2P fails, the system should fall back to relay — if even that fails, the router may be filtering outbound UDP entirely.
Solutions
Section titled “Solutions”1. Enable TCP fallback on the SMX-RNS20
Section titled “1. Enable TCP fallback on the SMX-RNS20”Log in to the SMX-RNS20 web interface and navigate to Network → WAN settings. Enable the TCP Relay option if available in your firmware version. This forces the tunnel to use TCP over port 443 (HTTPS), which almost all routers allow.
2. Check router’s UDP filtering settings
Section titled “2. Check router’s UDP filtering settings”Access the Alcatel router’s admin panel and check for any UDP timeout or firewall rules that may be blocking outbound UDP on ports above 1024. Setting a longer UDP timeout (≥ 120 seconds) can resolve intermittent drops.
3. Use a SIM card with a different operator
Section titled “3. Use a SIM card with a different operator”If the SMX-RNS20 uses a mobile (SIM) WAN connection through an Alcatel router, try a SIM from a different mobile carrier. Some carriers apply Carrier-Grade NAT (CGNAT) that blocks direct P2P. Switching to an operator that provides a public IP resolves the issue.