VPN (pptpd) stopped working

[j.halifax .]

Hi all,

Could you please advise, how to find why VPN which was working with pptpd stopped working? 

I was out and when I came I found the box down and since that time VPN is not working. 
- Windows client says Error 678 "The remote computer didn't respond" 
- (but I can ping it as 195.39.130.92) and 
- on the Internet port of the server 195.39.130.92 I can see the following traffic related to the VPN client PC:

# tcpdump -n -i eth0|grep "94.129.168.182" |grep -v "ICMP"
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
11:31:50.107939 IP 94.129.168.182.gw > 195.39.130.92.pptp: Flags [S], seq 3061761952, win 16384, options [mss 1460,nop,nop,sackOK], length 0
11:31:50.107967 IP 195.39.130.92.pptp > 94.129.168.182.gw: Flags [R.], seq 0, ack 3061761953, win 0, length 0
11:31:50.608848 IP 94.129.168.182.gw > 195.39.130.92.pptp: Flags [S], seq 3061761952, win 16384, options [mss 1460,nop,nop,sackOK], length 0
11:31:50.608869 IP 195.39.130.92.pptp > 94.129.168.182.gw: Flags [R.], seq 0, ack 1, win 0, length 0
11:31:51.228744 IP 94.129.168.182.gw > 195.39.130.92.pptp: Flags [S], seq 3061761952, win 16384, options [mss 1460,nop,nop,sackOK], length 0
11:31:51.228762 IP 195.39.130.92.pptp > 94.129.168.182.gw: Flags [R.], seq 0, ack 1, win 0, length 0

Thank you for your help!
jh