I have had similar issues to this at my own office network as well as with one of my clients. The error 619 seems to persist for some time then will automagically clear and sometimes will get a great stable connection. Other times, I will get the 619 10 times in a row, then a connect, but it will only stay connected for a few minutes. I have tried full resets of the dir-130. I have tried every conceivable combination of things to get any consistency from this. I have tried from different networks on different ISPs (Comcast and Verizon wireless) and it's just so undependable I don't know what to do with it.
It used to be that this was a very reliable connection but now it's flaky.
As an attempted fix for both myself and my client, I wanted to set up to pass the VPN endpoint to an RRAS server on the inside. This connection I've not yet been able to get to work no matter what I attempt to do. It indicates that the GRE protocol is not getting through. I've connected internally to this RRAS server, so I know the server itself isn't having a problem with accepting the required ports or protocols. I have also (as above) been able to make PPTP connections through my Comcast Business Router (with GRE being allowed through) and those work, so the only place I can see GRE getting blocked from getting to my inside network is AT the DIR-130.
I am at my wits end trying to get this to work and I can't even really figure out WHAT isn't working.
Please help!