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Connection Issues Troubleshooting

Troubleshooting Connection Issues​

It can be a little tricky to figure out why something isn't working. We'll try to improve this. Unfortunately you need to use the CLI to troubleshoot.

It's a peer to peer system, so we might need to check 2 or more nodes to deduce where the problem is.

Go through these steps and see corporate firewalls and Router Tips for more explanation.

Peers List​

Check this command on both peers

zerotier-cli peers

If one device has many "RELAY" connections, it's having a hard time connecting to things.

If the connections to the PLANETs are RELAY, the node is having a very hard time. UDP traffic may be blocked.

Status​

zerotier-cli info it eventually says "RELAY" instead of "ONLINE" if UDP traffic is blocked.

Checking for Symmetric NAT​

zerotier-cli info -j

Look at the "listeningOn" and "surfaceAddresses". If the surfaceAddress list large is constantly growing for each node you ping, this node may be behind Symmetric NAT. Other devices will have a hard time connecting with it. See corporate firewalls for more info on Symmetric NAT.

Ideally there is 1 surface address for each listening address/port.

For a simplified example, if your computer only has 1 network interface and IP address, listeningOn will look like this:

"listeningOn": [
    "192.168.100.193/9993",
    "192.168.100.193/55957",
    "192.168.100.193/30431"
    ]

then the surfaceAddresses should have only 3 entries

"surfaceAddresses": [
    "198.51.100.9/24/9993",
    "198.51.100.9/30431",
    "198.51.100.9/2785"
   ],

Usually there is more going on in these entries and it can be hard to read. The output of zerotier-cli dump contains this information. If you send it to us, we can read it for you.