IPSec VPN and L2TP

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BMS
BMS Posts: 21  Freshman Member
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edited August 2021 in Security
I have a USG210 running multiple IPSec VPN connections to other offices.  It looks like if someone connects to an L2TP session with a remote workstation at least one of those IPSec sessions drops.  Is this something in configuration or something anyone else has experienced?  I've never noticed it on any other system.

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  • mMontana
    mMontana Posts: 1,300  Guru Member
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    In number, what "multiple" means? 50? 100?
    Is a specific IPSec gateway configured only for L2TP or is "shared" with a Tunnel?
    Does subnets don't overlap?
  • BMS
    BMS Posts: 21  Freshman Member
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    Okay, it's 5 IPSec VPN.  The IPSec gateways are unique for each VPN connection.  There is no visible subnet overlap, though that was my first thought as well.  One of the remote VPN connections is not controlled by me, so there could be something buried in there I am not aware of though.  Would that explain that kind of quick drop?  It only drops for a second or two, but that's long enough to disrupt connections.  They use RDP on one of the VPNs exclusively and that is the one having problems.
  • Zyxel_Cooldia
    Zyxel_Cooldia Posts: 1,450  Zyxel Employee
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    Hi @BMS,
    Can you send me USG-210 configuration file in PM for further checking?
  • BMS
    BMS Posts: 21  Freshman Member
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    That has been sent
  • mMontana
    mMontana Posts: 1,300  Guru Member
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    edited August 2021
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    BMS said:
    There is no visible subnet overlap, though that was my first thought as well.
    Even into remote subnets and L2TP Subnet?
    Would you please share all the subnets of your setup?
  • BMS
    BMS Posts: 21  Freshman Member
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    None that I have found.  I've asked the other end of the VPN connection affected and they confirmed they do not use a 192 address at all.  In addition, it only interrupts for a few seconds, then the connection works again.

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