VPN to Zscaler ZIA with Sim from ISP that uses cgnat

Hi guys,

I try to setup a vpn from a sdx pro to Zscaler ZIA.
Unfortunately, my mobile-provider uses carrier grade NAT to hide my public IP. Anyway, I would assume that this should still work, as I do initiate that connection from the peplink device, not the other way round… But I don’t get the connection running…

Best regards
Linus