Location dependent "Disconnected" servers

Thanks for the development of this open source software!

I have been attempting to connect two servers with Syncthing. I have been able to get them to connect and share the ~/Sync repository when one node is at home and the other is at work (at least the node at home can connect to the one at work). But, the two servers show as “Disconnected” when both machines are at work. I am guessing this is a simple networking issue, but do not have sufficient experience to debug.

I ran a tcpdump while at work and it appears as if both nodes are receiving and sending packets to each other, but the interface is dropping connections on one node.

Node A (laptop):

tcpdump -n -i eth0 -X port 21025 4 packets captured 4 packets received by filter 0 packets dropped by kernel 32 packets dropped by interface

Node B:

tcpdump -n -i eth0 -X port 21025 9 packets captured 9 packets received by filter 0 packets dropped by kernel

Any help, or at least a place to start–appropriate diagnostic tools, etc—would be much appreciated!

Thanks, Ben

Port 21025 is the local discovery protocol. You might be looking at your outgoing packets only, can’t say without seeing the actual data. Are the machines on the same network? Can they ping each other? Is there a local firewall? Those are all things to check.

Hi Jakob,

Sorry for such a late response.

Yes, the machines are on the same network and each one can ping the other. There is no local firewall other than Ubuntu’s default “ufw,” and CentOS’s iptables, but as far as I understand, the firewall configuration is not dynamic, so I wouldn’t expect different behavior on different networks. At least I have not configured the firewall to have different behaviors on different networks.

I did just now disable ufw on my mobile node (Ubuntu) to see if the status of the other node (CentOS) would change. No dice…

What other ports should I check?

Thanks for your help!, Ben