Hello,
I've a strange issue with SSH connections over my VPN tunnel. I've configured the VPN connection with this tutorial. All works as expected. I can connect to my AWS instances over SSH, execute commands and so on. I can also connect from inside the AWS VPC to my local instances. But I cannot send files which are over 1330 bytes large to my remote instances. Sending a large file from an AWS instance to my locale instance works as expected. I've alos an issue if I create a SSH connection from an AWS instance to my local machine. The connection works but if I execute a command which outputs data to the console, the SSH connections hangs. The other way arround this works as expetced.
send file -> local to AWS -> failed send file -> AWS to local -> works execute top -> local to AWS -> works execute top -> AWS to local -> failed
Can this be an MTU issue? The VTI interfaces are configured with an MTU value from 1436. If I configure the VPN with a tunnel instaed of a VTI all works as expected. I've read that it's a common issue with SSH and MTU and so I tried to set the MTU on the AWS instance to 576, and behold, the issue is gone!
But is setting the MTU to 576 for all AWS instances really the solution for this issue? I'm sure that in our company office that we have set also the MTU to 1436 on the router(Zyxell Zywall). And there we do not have such an isssue.
Any help would be really appreciated!
Best regards,
Christian