Issue
The Socket fails to establish a DTLS tunnel to the Cato Cloud when connected to LTE/5G providers such as AT&T Mobility, despite having active internet access through the ISP.
Environment
Physical Socket
LTE/5G Provider
Troubleshooting
Refer to Socket Site Tunnel Connectivity Troubleshooting to gather detailed connectivity information and PCAP captures from the Socket WebUI.
Verify that the Socket can successfully ping well-known public IP addresses (e.g., 8.8.8.8) via the WAN port.
Ensure that there is bidirectional DTLS traffic over port UDP/443 on the WAN connection. This can be checked in the PCAP capture obtained in the first step.
Further, analyze the PCAP capture for any signs of interference from the ISP during the DTLS handshake. Look for carrier-specific data (e.g., APN information) within the packet payload.
Solution
Some LTE/5G providers might interfere with DTLS connections on port UDP/443. To resolve this issue, change the DTLS port to UDP/1337 via the Socket WebUI as explained in Setting a Different Port to Connect to the Cato PoP