Site to Site VPN disconnects

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Trinity99
Posts: 2
Joined: Tue Apr 04, 2017 10:39 am

Site to Site VPN disconnects

Post by Trinity99 » Tue Apr 04, 2017 11:08 am

Dear all,

I´ve setup SoftEther on 2 sites (different IP networks), I can connect and ping through the VPN but after
around 8-10 pings the connection drops and come up again after around 10 seconds for 8-10 pings then down again.... but I can´t see any disconnects in the SoftEther log files.

My setup is:

Main site: (Germany)
- VPN Server on Windows
- Virtual Hub 1 bridged to physical network card
- Virtual Hub 2 for cascaded bridge connection to second site
- L3 Switch with 2 virtual interfaces
- Int 1 with IP address from main site linked to virtual hub 1
- Int 2 with IP address from second site linked to virtual hub 2

Second site: (China)
- VPN Bridge on Windows
- Virtual hub bridged to physical network card
- cascaded connection to main site virtual hub 2

establishing the connection is very fast (2 sec) and also the ping response times are acceptable for a connection from China to Germany.
I also noticed that in the moment when the ping stops, my CPU load on the VPN server is very high (60-80%) and as soon the ping goes through, the CPU load becomes normal. (Only on server site, second site is normal all the time)

Thanks in advance for any help
Ivo

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: Site to Site VPN disconnects

Post by thisjun » Thu Apr 13, 2017 5:41 am

I doubt a packet loop may be formed.
Did you use secureNAT?

Could you show a server log?

Trinity99
Posts: 2
Joined: Tue Apr 04, 2017 10:39 am

Re: Site to Site VPN disconnects

Post by Trinity99 » Thu Apr 13, 2017 3:52 pm

I didn´t use secure NAT.
I already removed the test installation so I can´t provide any log files.
As soon I´m back from my business trip I will give it another try and will report. (in around 2 weeks)

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: Site to Site VPN disconnects

Post by thisjun » Wed May 10, 2017 6:18 am

There are some report that VPN connection with UDP over NAT becomes unstable.
Please try to check "Disable NAT-T" and check "Disable UDP acceleration".

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