A TCP reset does not prove your VPN is being blocked

Connection reset, restarting appears in the client log, and the conclusion arrives before the evidence does. Someone decides the network is blocking the VPN, or the certificate is wrong, or a specific country is interfering. A reset is a TCP packet that ends a connection, and the log line records that your client received one. It does not name the device that sent it or the reason it was sent.

A reset is a packet, not a verdict

TCP defines reset processing: a segment with the RST flag ends the connection immediately. The receiver does not negotiate, retry, or ask why. It reports the reset and moves on.

That is all the client knows. The RST could have come from the server, a proxy, a firewall, or a load balancer that lost state.

Attribution is a separate exercise. An apparent source address in a capture is not proof of the physical origin, and it says nothing about the policy decision behind it. Middleboxes can spoof addresses, and stateful devices can reset on timeout rather than intent. Treating the reset as a verdict skips the part where you find out.

Confirm which connection was reset

First check that the active profile actually uses TCP. A reset on a UDP tunnel makes no sense, and a log from an HTTP proxy can concern a different TCP leg than the VPN itself.

Record the destination, port, attempt time, and the stage the client had reached.

The stage is the most useful field. A reset during the TLS handshake points at one set of suspects; a reset after authentication points at another. Without the stage, every theory fits.

Compare both ends of the path

If you administer the server, compare its events for the same attempt. Did it accept the connection? Did it close it deliberately? Did a reply leave one boundary and never arrive at the next?

Capture at the client and at the server if you can. A reset that appears at the client but not at the server did not originate at the server.

Watch for RST segments in both directions:

sudo tcpdump -ni any 'tcp[tcpflags] & tcp-rst != 0' -c 20
ss -tnp | grep 198.51.100.20

Narrow with a controlled comparison

A second approved network can tell you whether the failure follows the client or the path. If the same profile works elsewhere, the client configuration is probably fine and the path is the variable.

That still does not identify one middlebox. It narrows the scope to a route, which is a useful and honest result.

Keep the distinction between this path fails and this named actor caused it. The first is testable; the second usually is not from a single client.

Check the fix without changing trust settings

Do not disable TLS verification, regenerate credentials, or announce a blocking policy from one reset line. Each of those changes the system under test and makes the next comparison meaningless.

Fix the identified component through its owner, then repeat the same profile and the same observation:

openvpn --config client.ovpn --verb 4
sudo tcpdump -ni any 'host 198.51.100.20 and tcp' -c 40

The useful outcome is a better-located failure, not a more confident story. If the reset disappears after a proxy fix, you have a cause. If it moves to a different stage, you have learned something about the path. Either way, the evidence should be able to survive a second person reading it. Write down what you observed, not what you concluded.