I have an OpenVPN connection which was initially over UDP. After some time I started to have serious hiccups when running ssh inside that tunnel.
As seen from inside the tunnel, ssh packets were lost, there were Host Unreachable ICMP messages - all this translated into a connection which was hanging all the time (and then back to normal, to hang again after some time).
From the perspective of the carrier interface, I was seeing a constant flow of encrypted packets (DATA_V1 and DATA_V2). The OpenVPN server was stable (no disconnection / reconnection form the client).
I switched to TCP and all the problems are gone.
I now would like to understand which part of the connection is at fault.
Topologically speaking, the client and the server are ~10 hops away, with a RTT of 12 ms. The networks are presumably solid (the client, after leaving a solid corporate network goes to Level3, peered with Orange, which itself brings FTTH).
Is there a reasonable way to check whether the UDP issues are close to any of the ends (corporate or home)?
Note: I understand that UDP is by nature a protocol which expects losses. Due to the "solidity" of the network, they however seem to be way too important.
