Comment 2 for bug 155945

Well after checking some info a little bit (i went on doubt) i've found this

http://forums.whirlpool.net.au/forum-replies-archive.cfm/524810.html
http://www.astaro.org/archive/index.php/t-13213.html

My previous post was based on real world experience with a customer, 2 remote locations with 2 pptp clients at each site. it wasn't possible to connect both vpn's. In fact i've found at the time some comment stating that this wasn't possible at all but couldn't find it to paste it here.

But according to your log posts could it be that the router gets confused with the natted connection?? and some kind of interaction with ubuntu TCP/IP stack?

maybe you can try to sniff some traffic and looking at upstream something about this.