Ubuntu + GSM modem

[rotterpotter]

Hello,
I installed ZeroTier on Ubuntu with a GSM modem, and it was assigned the address 172.29.85.26. On another machine (a Mac), the address in the network is 172.29.201.136. Pings between the machines are not working. In the zerotier-cli peers list, I don’t see the IP address of the other machine, and some existing entries have the status “Relay.”

[consti]

Hi rotterpotter,
it looks like your machines are using “Relay” mode in ZeroTier, which suggests they’re not able to establish a direct connection. Here’s how to troubleshoot:

1. Check Network Status:

• Ensure both machines are online in the same ZeroTier network:

  zerotier-cli listnetworks
  

2. Check Peer Status:

• On both machines, check the peer list:

  zerotier-cli peers
  

• Look for DIRECT status. If it shows RELAY, they’re routing via relays due to NAT issues.

3. Firewall/NAT:

• Ubuntu: Disable firewall temporarily:

  sudo ufw disable
  

• macOS: Allow ZeroTier through the firewall.
• GSM Modem: GSM modems may have restrictive NAT. Try forwarding UDP port 9993 to your Ubuntu machine.

4. Keepalive Settings:

• On Ubuntu, set keepalive to prevent idle connection drops:

  sysctl net.ipv4.tcp_keepalive_time=120
  

5. Logs:

• Check ZeroTier logs for any errors:

  sudo journalctl -u zerotier-one
  

6. Test with a Different Network:

• If possible, test on a non-GSM network to rule out GSM-specific issues.

These steps should help resolve the connection problems. Let me know if you need more details!