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First of all I believe this is a ESXi issue but let me know if you have seen this. It started about a year ago when I noticed occasionally when I putty via SSH to my VM guests, if I do anything that makes it to display a lot of things at once, the session will hang and I have to start a new one quite often only to find the same behaviour. What I meant by display a lot of things can be any of the following:
1) tail -f filename
2) Paste a long command
3) less filename

If I type in one character at a time this won't happen. I tried searching online and it always point me to flow control settings and the various suggestions I've tried have never been able to resolve the issue.

Since last week, I've noticed I'm not able to connect to my POP3 server from Outlook (it's timing out from Outlook's perspective).

Today I tried to connect to the ESXi via vSphere client and it gives me a time out also. Exact behavior and error I saw is similar to the one posted at the following URL but the suggested technique also failed to resolve the issue. http://davidcocke.blogspot.hk/2012/02/unable-to-login-with-vsphere-client.html

Has anyone experienced this before? Any suggestions on how to troubleshoot this?

user192702
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1 Answers1

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This is probably an MTU issue; i.e. fragmented packets. Are you on a VPN?

Can you describe what path you're taking to connect to these guests from your computer? What's in between you and the server(s)?

ewwhite
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  • Thanks for commenting. I just noticed that this is not limited to the ESX and the guests running on it. I have a separate physical box that is also giving me the same problem. The path goes from My PC -> Firewall (XTM21) -> Internet Router -> Internet -> Firewall (XTM505) -> Boxes. And yes between XTM21 and XTM505 it's a BOVPN. – user192702 Nov 10 '13 at 13:55
  • It's an MTU issue. I don't know how much control you have over the infrastructure, but if there's a dedicated network person, that's where you should start. – ewwhite Nov 10 '13 at 13:58
  • Sorry I'm the only one. I tried pinging from my PC to the boxes on the other end using packet sizes 1500 up to 3500 bytes and it's fine. Is this not an indication that this is not a MTU problem? – user192702 Nov 10 '13 at 14:07
  • Okay I'm unable to paste the ping results here because I can't enter new lines in comments. So I have started a new question on the maximum allowable MTU size at http://serverfault.com/questions/553963/maximum-mtu-size. You can see the ping results there. – user192702 Nov 10 '13 at 14:17
  • Okay so apparently I have to enable the Don't Fragment option and yes the MTU is found to be 1363 bytes. Am setting my PC to have MTU = 1200. Thanks! You saved me! – user192702 Nov 10 '13 at 14:44