unable to create a global protect VPN connection while carrier using Dual stack lite

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unable to create a global protect VPN connection while carrier using Dual stack lite

L0 Member

We are receiving many reports about extremely slow and unstable GlobalProtect connections with some internet providers in Marburg .
The providers don’t provide native IPv4 addresses in consumer tariffs, IPv4 packets are tunneled via carrier-grade NAT (Dual Stack lite). This causes packet fragmentation. End user are unable to connect to VPN or if the connection was etsablished, it is very slow (like a modem) an not stable.

As IPv4 address blocks are becoming depleted, even in other countries like Great Britain our affiliates reporting first issues with Dual Stack lite.
Temporary decreasing the MTU size may could help for a limited time but is not a solution. MTU size varies day to day and with our monthly driver updates, we automatically changes the settings back to "standard".
In the past year, we found a temporary solution. Customers were able to call the provider’s hotline and request DualStack configuration for additional 3€/month, but it’s not guaranteed to be persistent.


L4 Transporter


We were facing the same issue with DSLite.

You can set the MTU on the tunnel interface on the firewall (Advanced tab), a value of 1300 works fine for us.

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