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I will start off by saying - my issue is very odd and I really have no idea where to start searching.

Alright the introduction:
I have got:
MS 2008 PPTP vpn server
OpenVPN on Endian Firewall server

All are on the same network all hostnames resolve fine (ping) but the main CAS array gives a (DUP!) behind every ping (in Ubuntu only).

64 bytes from icmp_req=1 ttl=127 time=292 ms
64 bytes from icmp_req=1 ttl=127 time=293 ms (DUP!)
64 bytes from icmp_req=2 ttl=127 time=294 ms
64 bytes from icmp_req=2 ttl=127 time=294 ms (DUP!)

My client (laptop) is on the other end of the world in China these days.

2x CAS using Loadbalancing
2x Mailbox database servers
All have Exchange 2010 SP1 (i believe rollup 6)

VPN servers have been tested in combination with Exchange on windows - no issues.

On Ubuntu however.. it seems to behave odd. if I go to the OWA url --> it loads up fine both with VPN on AND off.

However there's one major difference:

with VPN ON
If i do anything inside owa (like checking a email - marked for "read") or simply send a message.. save a message etc --> It does not push through the changes (it stays on "saving")

OWA seems to respond faster, and every function works as it should.

Now of course this is not the original issue but this is on top of the rest of the problem.

My original problem was Exchange Mapi - It works but takes AGES to load (and seems to do nothing only very few times it pulls in messages- the rest of the time it stays loading). Unfortunatly i can not test Exchange mapi external (without vpn) as it uses port 135 - which by most providers: are blocked.

I have no idea where to start.. I'm pretty sure it's located in the VPN settings. for pptp:

Point to point encryption (MPPE) (128 bit)
Allow Stateful encryption
Send ppp echo packets

Point to point encryption is not optional unfortunaly MS PPTP will not connect to Ubuntu without it.

for OpenVPN:

Connection method is password. Use a TAP device is turned on (for some reason it will not connect without it.)

Any information, or help on where to check for errors will be very helpful.

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up vote 0 down vote accepted

My answer was "simple" - it was my MTU.

After reading the post on:, it began making a lot of sense. Everything works as it should now, it was just 2 simple extra strings in OpenVPN.

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