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VPN Performance (IKEv2) - Bad with VDSL - Good with Fibre

Hello,

we use Microsoft Always On for all Mobile and Home Office Users.

These clients connect to their home routers and connect to a public IP of our XGS2100.
The Firewall uses a symetric Fibre connection (100MBit) from German Telekom.

XGS has forwarding rule to the internal RAS Server.

SSL/TLS is currently disabled, IPS is disabled for this firewall rule at console level.

We have different situations with/without any problems

Users with a Fibre (400/200) at Deutsche Glasfaser have no problems.
Users with a VDSL  (250/10) at German Telekom have no problems.
Users with a VDSL  (100/50) at German Telekom have no problems.

But only some have problems with a VDSL Connection at German Telekom?

They use a AVM FritzBox, LANCOM R884AV, Speedport Router and all share the same problem.
Performance for MS AlwaysOn is terrible slow, they have disconnects, and no connections during the day.

I tried to change the MTU at Client Side (1300-1400) that didn´t change anything.
I changed the MTU at Internet Side in LANCOM Router <-> VDSL to 1400 and a few minutes this was better.

But most of the settings didn´t work at all.

Is there anything i could verify/change at Firewall (XGS 18.5.4) level?

I tried some TCP Dumps at Client Side, it doesn´t matter if the client uses WiFi (Connected to XGS2100) or a VDSL Internet Connection.
TCP Dumps shows a lot of TCP Retransmissions in both connection.

 But WiFi Connection and performance is good.

Has anyone solved these VPN performance Settings at Firewall Level?

Thanks

Jürgen



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Parents
  • I am not sure, if this is really something, based on the Firewall? I would look into the RAS and Microsoft Support first. 

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Reply
  • I am not sure, if this is really something, based on the Firewall? I would look into the RAS and Microsoft Support first. 

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Children
  • I checked RAS and Hardware Router Support already.

    i checked other things...

    the connection to a SQL Server (SQL01) is terrible slow.
    the connection to a SQL Server (SQL02) is fast.

    Both Servers are on the same Hyper-V Host, one is a Windows 2008 (fast), the other a Windows 2016 (slow) VM.
    very strange 

  • Hi juergenb52

    Need more information like you connecting the user with IPSec VPN(remote access), SSL VPN(remote VPN), or site to site?

    Regards

    "Sophos Partner: Infrassist Technologies Pvt Ltd".

    If a post solves your question please use the 'Verify Answer' button.

  • Not sure, how the appliance should cause this. You could perform two tcpdumps on the appliance and check both dumps. Do not know, if the appliance is even involved in the post VPN traffic (RAS server to SQL). But i dont know, how to debug this. If you say, its not all servers in your network, this sounds specifically like a network issue. 

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