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I have a PPTP server setup at home, which I connect to from my work's network. I can connect to it without any issue, but when I try to upload files, I lose connectivity to it about 1mb into the transfer. I'm not disconnected from the VPN, but the file transfer hangs and I am no longer able to access any internet sites. I can restore connectivity by disconnecting from the VPN and then reconnecting.

I setup an OpenVPN server at home too, and am able to upload files without any issue over that, but I do not want to use OpenVPN, only PPTP.

I've been struggling to diagnose this one, but think it might be because of an MTU issue, simply because others have reported similar problems. If this is the case, I am unsure where to change the MTU value.

The values I know are these:

My PPTP server is configured to use MTU 1400. My Home Network's router is configured to use MTU 1500. My client computer is using an MTU of 1400 for the PPTP client interface (from work network).

Given these values, does anyone have any recommendations on what I should change the MTU values to, and where? That is, of course, unless anyone thinks the problem may lie elsewhere.

I've also tried transferring files from three different client machines (on work network), but all have the same problem.

Regards, Nick

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Take a look at the accepted answer to this: serverfault.com/questions/376752/… –  cjc May 16 '12 at 10:13
Thanks cjc, it's a very comprehensive answer, but I'm not sure that it helps me. I attempted to translate his ping command to windows, and tried ping -f -l 1472 google.com and get "Packet needs to be fragmented but DF set.", which according to his answer implies that I don't have an MTU issue. But if I don't have an MTU issue, what could be the cause of this? –  dark_perfect May 16 '12 at 10:49
indeed I think it could be a MTU issue. Did you try to set the MTU at 512 (for example) on the both side ? –  eVoxmusic May 16 '12 at 11:45
When you say "both sides", where do you mean exactly? I can change it on my client machine, which would be my side, but I can change it on the router and the vpn configuration server side. –  dark_perfect May 16 '12 at 11:53
Yes I mean the VPN server and your client. –  eVoxmusic May 16 '12 at 12:17

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