Re: Connecting to resources over a SBS 2003 VPN

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Neil TCC wrote: 
Hi Edward,

Thanks for your reply, the problem i am getting is error 721 The remote computer did not respond, this happens when i attempt to connect from a second client after the first one is connected.

It gets as far as the verifying username and password and then gives the 721 error.

I have followed your instructions in the prvious message but am still getting the same problem


This is more likely to be a function of your router than of SBS. I had
a quick look but can't see any mention of your router hardware. Routers
all broadly do the same things, but individual details can vary widely
and can be difficult to ascertain. One of these details is how many
simultaneous VPN connections can be maintained.

You may be aware that a PPTP VPN uses port 1723 of the TCP protocol, and
also protocol 47. The user verification, followed by error 721, is
usually a sign that protocol 47 is not getting through. 1723/TCP is
concerned with VPN control and other 'housekeeping', and all the data is
carried on protocol 47. It is entirely possible that the router is
capable of keeping track of many simultaneous TCP connections, but only
one protocol 47 connection.

This type of detail is rarely found in the router specification, unless
its manufacturer wants to boast about a particularly large number of
VPN tunnels supported. My advice at the moment would be to try to get
hold of another router, at least on loan, to see if the problem still
occurs. I'm not familiar with a range of hardware, but I know that the
Netgear DG834 can support at least two PPTP VPNs.

Another thought occurs: you didn't (I think) say whether the second
client was at the same physical location as the first. If so, that adds
a further level of complexity, in that the routers at both ends have
to be able to keep track of simultaneous connections on the same ports
between the same two IP addresses, and yet sort out the message streams
to the right machines at the remote end. This is also an undocumented
area where all routers are not created equal. I'm not even certain that
SBS can keep track of multiple VPNs apparently originating on the same
remote IP address. Probably it can, or we would know otherwise by now.

.

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