On Mon, Feb 12, 2018 at 08:05:18PM -0500, H wrote: ... > Not sure if I am reading your reply correctly but I should clarify > that I have problems when running naked ssh to the server, when I > run ssh to the same server but over the VPN connection (that goes > via third server) everything is flawless. > > I should also explain that: > > - I am on a workstation (located in the US), ssh-ing into server 1 > (located in the US). > > - From server 1 I use scp to transfer large files from server 2 > (located in Europe) to server 1 (in the US). > > The above randomly disconnects. You have two ssh sessions here. AFAICT, it's the first one (workstation->server 1) that randomly disconnects, right? > > However, when: > > - I use a VPN connection to server 3 (also located in Europe). > > - From the same workstation as above, do exactly as above, > connections are rock-solid. It would seem to me that something between your workstation and server 1 is possibly mishandling TCP options (being it sack, timestamps or both). Is there a router or a firewall in between? Try doing a traffic capture between both and see why it hangs. If you're hesitant to post the binary traffic capture, post the text version of it with anonymized IP addresses. Just please be sure to disable ssh protocol so it would include TCP details on it then. Marcelo