Problem with Wireguard through Speedfusion-Cloud

Hi!

I currently have a strange problem and could use an 'idea.

Setup:

  • Peplink B One 5G
  • Client on B One 5G with Wireguard

→ When the client connects directly through a WAN connection, Wireguard works perfectly.
→ When the client connects through its own on-prem Speedfusion tunnel, Wireguard works perfectly.
When the client connects its wireguard-session via SFC Cloud, ICMP is working through the tunnel, but nothing else does. MTU is already set to 1300 on both sides.

Do you have any ideas about this?

Thank you and best wishes
KPS