Thnx antioed,
what we have here is good ol' Microsoft VPN client that comes with every windows since stoneage (win2000 in my case).
Microsoft VPN client needs two devices, named "WAN Miniport (PPTP)" and "WAN Miniport (L2TP)", to function properly. Those devices are installed with OS and you can see them if you open Network adapters branch in Device manager, and check "Show hidden devices" in the View menu.
Stupid as I am, I unistalled those devices. Now my VPN connections are dead, as I already described. The problem is on *my side*, not VPN servers' side.
The problem is, you can't reinstall Microsoft VPN client, its kinda embedded in windows. Nobody seems to know how to get those devices back, in human way. I think I'm going to have to manually restore all registry entries involved. Gosh I hate that thing.
Wapper