I've got a Vigor 2860 with a simple dial-in L2TP VPN service set up that works fine for a couple of users but they can only connect one at a time. If one user is connected via VPN to the router then the other user can't log in. They get an error at their end saying the VPN server did not respond. Both users are assigned their own unique static IP addresses and everything seems to work fine as long as they don't both try and connect at the same time.

Any ideas on what's going? I've gone through all the settings but can't spot anything obviously restricting multiple users. I was under the impression the Vigor 2860 was able to handle more than one VPN user at a time.

Never mind, I solved the issue by upgrading to the latest firmware (3.8.9.4_BT)

Excellent, it's good to know the later firmware resolved your problem - typically I would expect multiple L2TP (or L2TP over IPsec) tunnels to work from the same remote IP.